I made two circuits in the 787-10 again yesterday afternoon in FS2024. Weather was the clear skies preset to avoid any influence of wind or nonstandard pressure. In each instance, as soon as the thrust reversers were engaged, the aircraft began tumbling and flying into the air. The second time I ran the test, I let the aircraft continue tumbling at full-reverse. As the tumble progressed, the aircraft altitude continued to increase to nearly 5,000’ AGL before I returned the engines to idle and closed the reversers. At this point, the asymmetric forces and weird physics glitch appeared to end - the aircraft began falling and passive-stability characteristics took over and dampened the tumble.
So based on what I saw, this seems to be a definite bug in the either the physics model of the sim or the way the 787 itself is modeled. I hope this gets changed to “bug-logged” soon and corrected in the first sim update.