I cannot hear calls on my Surface Duo 2 unless on speaker phone

I've also got the same problem. As well as this, I am unable to send group texts or mms. This has all occurred since the last update to Android 12 (I think).

We probably have different issues, or else you have TWO issues. My phone DOES send group texts and mms. It just doesn't have sound for phone calls unless I use speaker phone.

My phone is under warranty, and I finally contacted Microsoft (through the support on the phone itself) and they are shipping me a refurbished replacement and I'll ship them my defective phone.

Sam

I had this happen back in the spring, I think. A factory reset didn't do anything for me either. This was before the 12L upgrade, though. Unfortunately, I had dropped the device and the back glass near the camera bump was cracked. My only remedy was to get it replaced through warranty (though I had to pay ~1/2 the cost of the phone due to the physical damage not covered).

I'm not sure if that's what you want to hear, but that was my experience.

I suspect the bugs are to do with Android 12 update. I could do the same as you but don't want to change phones if I can avoid it and from reports, a swap may not fix it. I'll be interested to see if it fixes it for you.

https://youtu.be/MZGLVFdaiFY

Alas, my problem was before the Android 12. I was hoping it would fix it. But it didn't.

I'll let you all know if the swapped phone fixes things. (I didn't want to change phones either, but after doing the hard reset, I figured it was the same amount of work, so why not!)

Sam