I run the Evolution .46 both upright and inverted.

As posted it does run back... but if you have the engine properly tuned, at slightly above idle it should run back SLOWLY.

Try setting the throttle to idle and see how fast the fuel runs back into the tank.

If it takes 10 seconds or more, this sounds about right.

If it is relatively quick at idle, something is amiss.

( Or you have your needles set far too open... )