I just swapped my iphone 10 to iphone 12 pro and noticed that Im not receiving any of my group messages. I made sure to turn on mms messaging, group messagin, turned phone off and on, etc. Nothing is working.
i noticed that i was receiving them on my macbook but not on my new iphone.
If there are any group message threads that include you open on your friends devices from BEFORE you changed to your new iPhone, have them delete the thread and start over. Or you can try leaving the group, then have them add you again.
It may be an issue with their devices trying to iMessage your old iPhone.