Can receive but can't send MMS on AT&T prepaid Android
I have an LG Neon Plus on AT&T Prepaid (it is an AT&T device). A few weeks ago my phone started having trouble sending MMS (specifically pictures and group texts). About 99% of the time they fail.
I checked APN settings and also reset network settings, checked for phone updates, and restarted my phone. Mobile data is on and I still have 7GB of data left. WiFi calling is turned off. The problem happens whether I'm connected to WiFi or not. What else could be causing it?