This has been going on for several years now. If I send and/or receive too many MMS texts within a short period of time all future MMS messages lock up for a good 10-15 minutes (in rare occasions for a few hours). I'll try answering the usual questions I've seen pop up:
And to answer all the questions:
it's been happening for several years
it happens on multiple messaging apps that go through the VZ network (messages, messages+, vz messages) but it doesn't happen with wi-fi only networks like telegram and whatsapp
it's been happening across multiple phones: samsung, motorola
it happens with any group: I'm in several different texting groups all with different phone numbers and providers
it does not happen with my wife's iPhone
it happens in both Wifi and Data only, and it also happens when airplane mode is enabled
it also happens even after I've reset network settings too
Current phone seeing the issue is the S21
Current app being used is Google Messages