jahtripper Does this problem occur on a fresh factory reset device?
What did you change your APN settings to? I can tell you right now if you added "IMS" to anything, that's your issue. AT&T doesn't play well with any adjustment to that.
If you could, would you mind trying to create a new APN with the following:
Skip the mmsc/proxy/port for now
APN type: default,mms,supl,hipri
IPV4 for both regular and roaming
Mvno type: GID if you have their elite data packages, otherwise IMSI.
Save apn, select it, restart your phone.
Try that, if that doesn't work-- you have two options.. Factory reset, power off for 5-10m, turn on and test.
If THAT fails... Bother att incessantly and get comped for your time.