Since my S21 Ultra was new on a new ATT/Firstnet account I have had issues getting certain MMS messages. I will see "No Subject Message Size: XXKB Expires XXXX" press to download the message and nothing happens. It will not download until I turn wifi off and touch the message again to download.
If the text comes from a group message it will show as a text direct from the person who sent it. Once I turn off wifi to download the message it will show up under the group convo as expected. Sometimes when I get off wifi I instantly receive a text or two.. and I ask how long ago the person sent it and sometimes its hours.
I am using the default Samsung SMS app. ATT has swapped my Firstnet sim card and checked all the settings. It has been doing it since the first couple hours I've had it. It has happened on multiple wifi networks, not just my home network. I have tried switching texting app to google messages but that app has the same issue AND a different set of messaging issues (pics are over compressed to garbage even with advanced mms turned on)
I found an older thread on this will a "solution" that is a lengthy way of turning off wifi, but that only works one time. Next time someone tries to send a 2.5mb picture or certain even text only group messages while i am on wifi, it will do it again. That thread seems locked from replies while this issue still exists.
Ive had the phone probably 4 months now with this going on.