[Q] Straight Tall APN issue with SM-910T topic

So I recently got a T-Mobile Samsung Galaxy Note 4. As we know, it's unlocked 100% without any special root methods or entering in codes into the dial pad. With that being said, I popped in an LTE Straight Talk SIM card, transferred my old number to the new SIM and configured the APN and for a long while it was working fine with no issues. Then out of the blue, I had no data. It absolutely quit without warning. I go to check the APN settings I had previously and they were gone. I had redone everything and saved the settings. However, when I go back out a menu, no Straight Talk APN. I did the same thing again....and once again no APN settings. Just the default T-Mobile LTE APN.

So I'm at a loss. It was working fine previously and now I cannot set APN settings. I have reset the phone more than once (reluctantly). Any thoughts? Any help would be appreciated since I'm paying those bastards and some change a month for service I cannot get. Also as a note, I can receive and send text messages with no problem. Calling number results in "you are not registered on a network," but I know the fix for that.