Doc ,

I am definitely sure that ur CG is to far forward. Try moving it aft so that it is align with the trailing edge of the wing (or better yet, move it to the horizontal stab leading edge).

This way when u release the down elev ur Flip 3D will already be pointing up. U just need to gunned the throttle to recover to the hover.

Try it at ur own risk. Now if this work out, remember U got it from me!!!

May My Flip R.I.P
Hisham