Has any fix been found for you? I am having the same issue with an unlocked S9. It is random I will send one message then right after the next one will fail. I have to reboot the phone. Resetting network settings didn't help. It doesn't seem like a carrier issue. I haven't been able to test safemode because it works after I reboot regardless.
I'm having the same issue...can't send group messages (this is a new unlocked phone), can't send photos. I've never been able to do this. I've switched sim cards AND carrier! No one seems to be able to fix this issue! I've followed steps for troubleshooting this issue multiple times. Should I be returning the phone?
Why should I have to get a new sim card? It has only been an issue since the last update. So everyone that is having these issues needs to get a new sim card? This seems like a pretty common thing since the last update.
I have the same issue T-Mobile S10+ and previous S9+
Performed app clearing cache and data.
Check APN settings
Reset phone network settings
Clearing system cache
I called T-Mobile multiple times and I got with a Message specialist. Per our troubleshooting: The issue started from my S9 when updated to Android 9 / with Samsung One UI. Same issue with S10. They indicated the issue has been already reported to Samsung to fix something from the One UI that is causing this issue
I am having the same problem with my Samsung s9+. I bought it unlocked and I use straight talk and I've never had a problem with them before and it's just the group messages. When I got my phone in November, I didn't have issues with the group chats and it started in March 2019