I received this same DTC, P219a (Bank 1 AFR imbalance), when I used tunes from Bama. After several phone calls and emails, I sent in a data log. The revised tune I received did not fix the issue and I have not received a response to any of my emails since. I chalked it up to a learning experience and switched back to another tune which does not cause this DTC.
I'm very interested to find out if they can solve this issue with your tune.