Are you running a separate UBEC? Or are you running the BEC from the ESC? On 12s you want to run an OPTO ESC and a separate UBEC The BEC on the ESC gets hot on 6s stepping down the voltage which can cause the ESC to shut down when you give it throttle. I Run OPTOs on all my bigger planes. It's a safety redundancy. Otherwise, you risk a brownout or a cut out in the air and lose control.
No I'm not running at separate UBEC, I have a ZTW Skyhawk 130A ESC High SBEC Current Output designed to meet high current application it's suppose to eliminate the need for a separate UBEC. Running Hitec HS-5085MG Digital Metal Gear Micro Servos.