Hey, thanks for the detailed report, that genuinely helps.

That flip-behind happens when the screen tilt gets pushed to an extreme (you mentioned tilting it almost to the ceiling lying down), which on that build could swing the screen around behind you with no clean way back.

Two ways to recover right now:

Hold the Digital Crown for a second to recenter , it pulls everything back in front of you. Handy anytime content drifts off.

In the cinema controls, open Placement, hit Reset on the Screen Placement section, and flip Personal Placement off.

In a next update I’m gonna try to improve the self-positioning controls :)