I kinda figured you had some experience, since you stated the other systems you'd done. I think Steve missed where you had stated that. I hadn't setup a micro beast myself but have the AR7200BX which is essentially the same. I am surprised that you are having this issue, because that's normally a very good unit, and very stable. I run them on my 2 450's.
I'm thinking that there is just something that was either inadvertently misadjusted on setup (sleeve hitting a stick changing a setting), or this blunder I did one time, thinking I was in regular setup, and was actually in the advanced settings adjusting around when I rechecked my work after setup lol.