Switched to TMobile 5 days ago. Was able to send and receive group texts until one day ago. I’ve got a solid connection both LTE and Wifi and made no settings changes prior to onset of this issue. Since onset of the issue, I’ve reset network settings and updated iOS operating system.
On my side, when sending, it shows that I have sent to the group but each member is receiving it as a single message from me. I am not receiving any messages from the group. Messaging to individuals is working fine.