That's odd, I never had that trouble w. the 2Y I had w. mine. I have a 1100kv medusa now, and it doesn't have any issues either. I have no idea what yours is doing. That's def not normal.
Both of mine were with a futaba 2.4ghz also.
What do you have the timing set to? Did you do the auto tune?
It does sound like some sort or phase sensing issue.
Forgot to ask if you have the new ESCs or is it the older ones with the older version of the software? If so, send it back to MGM to get an updated one.