Sending a message fails silently on polkit authorization error

I tried to send an SMS after running Chatty from ssh console, which resulted in PolicyKit error. However, the UI didn't indicate it in any way and I had to check the log in order to see why the other end haven't received an expected message:

(sm.puri.Chatty:2421): mm-sms-DEBUG: 02:05:48.669: Couldn't create new SMS - error: GDBus.Error:org.freedesktop.ModemManager1.Error.Core.Unauthorized: PolicyKit authorization failed: not authorized for 'org.freedesktop.ModemManager1.Messaging'

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