This is a great phone but I'm going back to my Note 2. I don't like big phones but I figured if I'm getting a big phone might as well go all out.
For anyone searching this issue I have discovered the problem.
Textra works but not over wifi connection on Tmobile and and MetroPCS. I contacted the guy from textra and he said that the wifi code is protected by tmobile and they wont give it out. I just had the same issue today with the Hangouts update with MMS.
It appears that LG or Tmobile were lazy and didnt want to include group MMS over the WIFI connection. This does work with the Samsung S4 and Note 2 though.