Missing group MMS with "Message expired or not available" error

I occasionally do not receive MMS group messages when using the Google Messages app, showing the error "Message Expired or Not Available". Most messages in the group chat come through, but occasionally (and often the first after a period of inactivity) are missed.

This occurs with RCS enabled or otherwise. I can avoid the issue by using a 3rd party texting app (Textra in my case), but that's not really a solution, especially since it doesn't support wifi texting.

This a known issue with carrier/phone combinations, but since I'm using a device approved for Xfinity Mobile (Pixel 4a), I don't expect it to happen here. There's a Google support thread here (the recommended solution isn't really applicable): https://support.google.com/messages/thread/18774467?hl=en