SMS/MMS not recieved in 4G (T-Mobile USA)

SMS and MMS are not recieved while device is on 4G. In Android, I had to work around this by switching the phone to 3G. I cannot confirm this will work right now as I am now experiencing this issue: https://source.puri.sm/Librem5/ModemManager/issues/15

I believe the core issue is that T-Mobile has proprietary code that it puts on Android to have SMS on 4G, VoLTE, and Wi-Fi Calling working. The workaround is to drop it to 3g or reverse engineer the code to get it to work on T-Mobile. If you are curious which code it is, I figured it out with a Google Pixel 3a and put the script to strip it out of a factory image for Android Pie Here:

https://github.com/chris4795/sargo-extract-vendor-files/blob/master/UsagePie.md