Did you ever find a solution. Facing this after moving a project from 4.27 to 5.3!
Looks like a bug in the new Chaos system.
Using the Projection options, it should be instantly resetting to the correct position but its not.
4.27 works perfectly obviously.
Also tried.
p.Chaos.Solver.SleepEnabled 0
p.Chaos.Solver.Joint.UseLinearSolver 0