Samsung S3 - Group Messaging Went Bad

[AC Question]

I've been using the Messaging app for years now, and using Group
Messaging successfully for years, also.

I have Group Messaging enabled.
I have Auto Retrieve enabled.

About a two weeks ago, this began to happen, and I haven't been able to
fix it.

Group text started coming thru as individual text and you then have to
"download" the text, and it then adds it to the group text,and it
disappears from the individual replier. For instance, I just got a
group text sent to 4 people.... My Messaging showed there were 4
repliers, and I had to hit download on each of the 4 repliers, and the
reply was the same, and once individually downloaded, each individual
reply disappeared, and the reply ended up in the group text thread.

I've googled and it seems I have all my settings correct. I haven't
changed anything, and I haven't done any ATT or Samsung updates.

BTW, my wife has the same phone with the same versiion 4.2.2, and hers
has been working just fine.

Any ideas?

I have tried rebooting, removing battery and SIMM, waiting a few
minutes, but nothing.