Check your routing of your antenna.

I have a Mini 6s in a glow trainer and it is clean. I have a 6EXAP Futaba radio. Make sure like what was said earlier that you have it set to PPM, not PCM. Turn the Tx on a couple of seconds before plugging the Rx battery in.

I am getting some glitching, but it only happens in a certain spot in the pattern.

Good luck and let us know if you find out what the problem is.
Curtis
P.S. Do you know if the ESC is armed when you get this flutter? Maybe a noise issue with the power stage.