UPDATE--
Just an FYI the "Solved" post is not correct, that was a mistake and i cannot undo . Back to the phone...
Here is what i have done so far:
After troubleshooting with ATT the next step was to go to the Apple store and have them take a look at the phone. The tech at the store insisted that there was nothing wrong with the phone "physically" but if i wanted to replace the phone to rule out the possibility of the hardware having any issues i could. So i did... he brought me a new phone i did a restore from backup done 20 minutes prior and began testing the phone. It was difficult to replicate the issue, and of course the issue did not occur @ the store, but we intended. Good thing i had some screen shots from my buddy showing the texts messages i was missing out on so i did not seem completely insane.
No luck in replicating the issue, the tech said it must be an issue with the OS and restoring from a backup will only bring over the issues, makes sense i guess.
So the next step in troubleshooting was to restore the phone back to factory settings on a fresh iOS9 install. This means i would lose all information on the phone that i could not manually extract.
I restored to a fresh version of iOS9 and began to re-sync as much as i could back to the phone and began to test the texting, specifically in group texts is where the issues was occurring. Since the issue is intermittent i had to give it a few days to get some results.
Few days have passed....the issue is STILL THERE! 😠
I am missing out on tons of messages from MMS/SMS group chats, i don't know what else to do at this point, the only other thing i could think of is going to ATT and getting a new SIM card and swapping it out. This is so frustrating...
If anyone has any solutions to this problem please share, this ***** 😟