Factory Unlocked GS6 SM-G920T having MMS trouble

[Calebbush20]

So I bought an unlocked galaxy s6 from bestbuy 16 days ago and since then MMS has worked intermittently. I have AT&T and have verified the APN to be correct. I can always send MMS be it a picture or group message but about 60% of the time I cannot receive these messages. I receive a notification to download the message but as soon as I click it it tells me download of the message failed. I have called AT&T several times and once the guy changed something in the data plan which allowed me to use visual voicemail again but the MMS issue still persists. Can anyone give me some help as to how to fix this?

 

[Calebbush20]

Anyone?

 

[Calebbush20]

OK so I was able to get it working and actually retroactively download the files messages by switching to Google messenger. Any ideas why?