Physics Actors disappear when constraints are applied.

I recently ran into an issue (4.27 and in 5) where a physics actor disappears in the scene when I play it. I see it in the blueprint and in the viewport editor, just not during any play or simulation.

This has worked for me before, but this problem just started happening today.

I am mounting a physically based VR machine gun, and it needs to be on a base. This usually works with adding a physics constraint, and when I simulate in the BP, it works, but as soon as I sim or play in the editor it's just gone. If I delete the physics constraint, it's back in the scene but of course, not usable.

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Has anyone experienced this issue with constraints?