Audio disappearing when secondary call is being rejected

With the latest ModemManager (specifically https://gitlab.freedesktop.org/mobile-broadband/ModemManager/-/merge_requests/580 and https://gitlab.freedesktop.org/mobile-broadband/ModemManager/-/merge_requests/568) having multiple calls becomes possible.
Calls currently does not support this however and autorejects any incoming calls if a call is already active.
While testing the latest MM I noticed the audio disappearing on the L5 when the secondary call was being rejected.
See this log from wys (starting wys -> starting a call -> receiving and rejecting an incoming call:
** (wys:3701): DEBUG: 14:08:21.269: Watching for ModemManager
Wys started with modem `(none)'
** (wys:3701): DEBUG: 14:08:21.271: Found card 'alsa_card.platform-sound-wwan', alsa: 'Modem'
** (wys:3701): DEBUG: 14:08:21.314: ModemManager appeared on D-Bus
** (wys:3701): DEBUG: 14:08:21.377: ModemManager interface `org.freedesktop.ModemManager1.Modem.Firmware' found on object `/org/freedesktop/ModemManager1/Modem/2'
** (wys:3701): DEBUG: 14:08:21.378: ModemManager interface `org.freedesktop.ModemManager1.Modem.Modem3gpp.ProfileManager' found on object `/org/freedesktop/ModemManager1/Modem/2'
** (wys:3701): DEBUG: 14:08:21.378: ModemManager interface `org.freedesktop.ModemManager1.Modem.Modem3gpp' found on object `/org/freedesktop/ModemManager1/Modem/2'
** (wys:3701): DEBUG: 14:08:21.378: ModemManager interface `org.freedesktop.ModemManager1.Modem.Simple' found on object `/org/freedesktop/ModemManager1/Modem/2'
** (wys:3701): DEBUG: 14:08:21.378: ModemManager interface `org.freedesktop.ModemManager1.Modem.Time' found on object `/org/freedesktop/ModemManager1/Modem/2'
** (wys:3701): DEBUG: 14:08:21.378: ModemManager interface `org.freedesktop.ModemManager1.Modem.Voice' found on object `/org/freedesktop/ModemManager1/Modem/2'
** (wys:3701): DEBUG: 14:08:21.378: Adding new voice-capable modem `/org/freedesktop/ModemManager1/Modem/2'
** (wys:3701): DEBUG: 14:08:21.380: ModemManager interface `org.freedesktop.ModemManager1.Modem' found on object `/org/freedesktop/ModemManager1/Modem/2'
** (wys:3701): DEBUG: 14:08:21.380: ModemManager interface `org.freedesktop.ModemManager1.Modem.Messaging' found on object `/org/freedesktop/ModemManager1/Modem/2'
** (wys:3701): DEBUG: 14:08:21.380: ModemManager interface `org.freedesktop.ModemManager1.Modem.Modem3gpp.Ussd' found on object `/org/freedesktop/ModemManager1/Modem/2'
** (wys:3701): DEBUG: 14:08:21.380: ModemManager interface `org.freedesktop.ModemManager1.Modem.Signal' found on object `/org/freedesktop/ModemManager1/Modem/2'
** (wys:3701): DEBUG: 14:08:21.380: ModemManager interface `org.freedesktop.ModemManager1.Modem.Location' found on object `/org/freedesktop/ModemManager1/Modem/2'
** (wys:3701): DEBUG: 14:08:56.140: Call `/org/freedesktop/ModemManager1/Call/12' added, state: 0
** (wys:3701): DEBUG: 14:08:56.208: Call `/org/freedesktop/ModemManager1/Call/12' state changed, new: 1, old: 0
** (wys:3701): DEBUG: 14:09:01.680: Call `/org/freedesktop/ModemManager1/Call/12' state changed, new: 2, old: 1
** (wys:3701): DEBUG: 14:09:01.680: Call `/org/freedesktop/ModemManager1/Call/12' gained audio from network
** (wys:3701): DEBUG: 14:09:01.680: Modem `/org/freedesktop/ModemManager1/Modem/2' audio from network now present
** (wys:3701): DEBUG: 14:09:01.680: Audio from network now present
** (wys:3701): DEBUG: 14:09:01.680: Finding ALSA card `Modem' source output
** (wys:3701): DEBUG: 14:09:01.681: End of source output list reached
** (wys:3701): DEBUG: 14:09:01.682: Instantiating loopback module for ALSA card `Modem' source
** (wys:3701): DEBUG: 14:09:01.682: Finding source for ALSA card `Modem'
** (wys:3701): DEBUG: 14:09:01.683: The source 0 `alsa_output.platform-sound.HiFi__hw_L5_0__sink.monitor' is not ALSA card `Modem'
** (wys:3701): DEBUG: 14:09:01.683: The source 1 `alsa_input.platform-sound.HiFi__hw_L5_0__source' is not ALSA card `Modem'
** (wys:3701): DEBUG: 14:09:01.684: The source 2 `alsa_output.platform-sound-wwan.stereo-fallback.monitor' is not ALSA card `Modem'
** (wys:3701): DEBUG: 14:09:01.684: The source 3 `alsa_input.platform-sound-wwan.stereo-fallback' is ALSA card `Modem'
** (wys:3701): DEBUG: 14:09:01.684: End of source list reached
** (wys:3701): DEBUG: 14:09:01.684: Instantiating loopback module with source `alsa_input.platform-sound-wwan.stereo-fallback' (ALSA card `Modem')
** (wys:3701): DEBUG: 14:09:01.853: Instantiated loopback module 47 with source `alsa_input.platform-sound-wwan.stereo-fallback' (ALSA card `Modem')
** (wys:3701): DEBUG: 14:09:04.746: Call `/org/freedesktop/ModemManager1/Call/12' state changed, new: 4, old: 2
** (wys:3701): DEBUG: 14:09:04.747: Call `/org/freedesktop/ModemManager1/Call/12' gained audio to network
** (wys:3701): DEBUG: 14:09:04.747: Modem `/org/freedesktop/ModemManager1/Modem/2' audio to network now present
** (wys:3701): DEBUG: 14:09:04.747: Audio to network now present
** (wys:3701): DEBUG: 14:09:04.747: Finding ALSA card `Modem' sink input
** (wys:3701): DEBUG: 14:09:04.748: Getting sink 0 of sink input 22 `Voice call audio (to speaker)'
** (wys:3701): DEBUG: 14:09:04.748: End of sink input list reached
** (wys:3701): DEBUG: 14:09:04.751: Sink 0 `alsa_output.platform-sound.HiFi__hw_L5_0__sink' is not ALSA card `Modem'
** (wys:3701): DEBUG: 14:09:04.751: Instantiating loopback module for ALSA card `Modem' sink
** (wys:3701): DEBUG: 14:09:04.751: Finding sink for ALSA card `Modem'
** (wys:3701): DEBUG: 14:09:04.753: The sink 0 `alsa_output.platform-sound.HiFi__hw_L5_0__sink' is not ALSA card `Modem'
** (wys:3701): DEBUG: 14:09:04.754: The sink 1 `alsa_output.platform-sound-wwan.stereo-fallback' is ALSA card `Modem'
** (wys:3701): DEBUG: 14:09:04.754: End of sink list reached
** (wys:3701): DEBUG: 14:09:04.754: Instantiating loopback module with sink `alsa_output.platform-sound-wwan.stereo-fallback' (ALSA card `Modem')
** (wys:3701): DEBUG: 14:09:04.781: Instantiated loopback module 48 with sink `alsa_output.platform-sound-wwan.stereo-fallback' (ALSA card `Modem')
** (wys:3701): DEBUG: 14:09:29.027: Call `/org/freedesktop/ModemManager1/Call/13' added, state: 6
** (wys:3701): DEBUG: 14:09:29.101: Call `/org/freedesktop/ModemManager1/Call/13' state changed, new: 7, old: 6
** (wys:3701): DEBUG: 14:09:29.161: Removing call `/org/freedesktop/ModemManager1/Call/13'
** (wys:3701): DEBUG: 14:09:29.162: Call `/org/freedesktop/ModemManager1/Call/13' removed
** (wys:3701): DEBUG: 14:09:38.269: Call `/org/freedesktop/ModemManager1/Call/12' state changed, new: 7, old: 4
** (wys:3701): DEBUG: 14:09:38.270: Call `/org/freedesktop/ModemManager1/Call/12' lost audio from network
** (wys:3701): DEBUG: 14:09:38.270: Modem `/org/freedesktop/ModemManager1/Modem/2' audio now absent
** (wys:3701): DEBUG: 14:09:38.270: Audio from network now absent
** (wys:3701): DEBUG: 14:09:38.270: Finding ALSA card `Modem' source output
** (wys:3701): DEBUG: 14:09:38.270: Call `/org/freedesktop/ModemManager1/Call/12' lost audio to network
** (wys:3701): DEBUG: 14:09:38.270: Modem `/org/freedesktop/ModemManager1/Modem/2' audio now absent
** (wys:3701): DEBUG: 14:09:38.270: Audio to network now absent
** (wys:3701): DEBUG: 14:09:38.270: Finding ALSA card `Modem' sink input
** (wys:3701): DEBUG: 14:09:38.273: Getting source 3 of source output 20 `Loopback to Built-in Audio Headphones + Speaker + Handset (echo cancelled with Built-in Audio Headset Microphone + Internal Microphone)'
** (wys:3701): DEBUG: 14:09:38.273: Getting source 16 of source output 21 `Voice call audio (from mic)'
** (wys:3701): DEBUG: 14:09:38.273: Getting source 1 of source output 22 `Echo-Cancel Source Stream'
** (wys:3701): DEBUG: 14:09:38.273: End of source output list reached
** (wys:3701): DEBUG: 14:09:38.273: Getting sink 8 of sink input 22 `Voice call audio (to speaker)'
** (wys:3701): DEBUG: 14:09:38.274: Getting sink 1 of sink input 23 `Loopback of Built-in Audio Headset Microphone + Internal Microphone (echo cancelled with Built-in Audio Headphones + Speaker + Handset)'
** (wys:3701): DEBUG: 14:09:38.274: Getting sink 0 of sink input 24 `Echo-Cancel Sink Stream'
** (wys:3701): DEBUG: 14:09:38.276: End of sink input list reached
** (wys:3701): DEBUG: 14:09:38.294: Checking whether module 47 for ALSA card `Modem' source output is a loopback module
** (wys:3701): DEBUG: 14:09:38.294: Source 16 `alsa_input.platform-sound.HiFi__hw_L5_0__source.echo-cancel' is not ALSA card `Modem'
** (wys:3701): DEBUG: 14:09:38.294: Source 1 `alsa_input.platform-sound.HiFi__hw_L5_0__source' is not ALSA card `Modem'
** (wys:3701): DEBUG: 14:09:38.294: Sink 8 `alsa_output.platform-sound.HiFi__hw_L5_0__sink.echo-cancel' is not ALSA card `Modem'
** (wys:3701): DEBUG: 14:09:38.295: Checking whether module 48 for ALSA card `Modem' sink input is a loopback module
** (wys:3701): DEBUG: 14:09:38.295: Sink 0 `alsa_output.platform-sound.HiFi__hw_L5_0__sink' is not ALSA card `Modem'
** (wys:3701): DEBUG: 14:09:38.299: Removing call `/org/freedesktop/ModemManager1/Call/12'
** (wys:3701): DEBUG: 14:09:38.300: Call `/org/freedesktop/ModemManager1/Call/12' removed
** (wys:3701): DEBUG: 14:09:38.301: Module 47 for ALSA card `Modem' source output is a loopback module
** (wys:3701): DEBUG: 14:09:38.302: Deinstantiating loopback modules for ALSA card `Modem' source
** (wys:3701): DEBUG: 14:09:38.303: Deinstantiating loopback module 47
** (wys:3701): DEBUG: 14:09:38.303: Module 48 for ALSA card `Modem' sink input is a loopback module
** (wys:3701): DEBUG: 14:09:38.303: Deinstantiating loopback modules for ALSA card `Modem' sink
** (wys:3701): DEBUG: 14:09:38.304: Deinstantiating loopback module 48
** (wys:3701): DEBUG: 14:09:38.304: Successfully deinstantiated loopback module 47
** (wys:3701): DEBUG: 14:09:38.305: Successfully deinstantiated loopback module 48
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Audio disappearing when secondary call is being rejected
