This looks like a thread safety bug that's been in the clothing system for a very long time.
Essentially a skeletal mesh component does a transform update and attempts to update the collisions of another skeletal mesh component while it's clothing task is in flight. Creating new collisions or removing old collisions is not permitted while the simulation is running and causes a crash.
Unsure what the solution here would be, previous skel meshes have triggered their clothing tasks so we really shouldn't mess about with it. Double buffering collisions is most likely the best option.
This isn't a regression, I've tracked it back at least to 4.13 but as long as we've had parallel cloth this will have been an issue.
1) Open ContentExamples
2) Open "Cloth" map
3) Move the first cloth piece over to the cloth-on-ball example
4) Select both pieces, enable environment collision, enable overlaps
5) Simulate
6) Select the ball object, move it into the other cloth and scrub it back and forth for a while
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-40716 in the post.