Physics Engine Seems a Bit Wonky

The wonky bit started with a cube I was pushing. I had it set up to try and lock the axis when you start pushing so it goes in a straight line that ended up with it jumping around the map and on other occasions if I surprised it flew into orbit.

Today I have had numerous crashes in a row from a simple set up to see if an idea would work.

Here is the gist of what I have.

Cube 1 at default size weight. Physics is locked only where it can move along the z axis to fly straight up. Also has a box collision so it can register an overlap consistently.
Cube 2 2 x bigger mass around 10 Physics default.
Seesaw actor basically cube default with about 3 Z, no physics. Another cube on top across it about the same length as the other was height, physics on, rotation limited to Y, parented to the other cube so it does not just flop down needs to be attached.
Cube 3 is elongated. Default everything except for its height which is about 3 as well. Blueprint event begin play, get player controller etc, then v key press play timeline loop to make it rotate along a specific axis because the player cannot push heavy blocks so this will be a controlled trigger til I figure out how to make that work.
Cube4: Actor with a larger hitbox attached for consistent overlap register attached to a ceiling cube static mesh.
That is about it. A very simple set up. Put the big cube on a tall wall, and put the small cube on the other end of the see-saw. Push Large cube off, hit seesaw, watch small cube fly up and hit the ceiling switch simple right wrong.

I was fiddling with other ideas a pivoting elongated cube with no timeline just rotated by the timeline cube. I got a crash while dinking with that okay no dinking with that. However I was curious as to something so I hooked up 3 to see how the rotation would play out and it crashed again was stuck on a crash loop the next time I opened it, it crashed again, and then again, and then opened the next time deleting what was set up okay. For serious no longer bothering with making gear puzzles got it. Went back to the simple ceiling switch idea just sitting and watching a bit to get the noodle cooking with what is working. Crashed. Okay. Open the software up again, dink with the puzzle again. Decide well I should just exit for now saves the project, hits the exit key while it is taking its time to exit crash asking to send a report. *Insert meme of fire everywhere and the dog sitting in the middle of it going this is fine.

Oh yeah, 4.19 though if I need to upgrade to the newer ones I can I guess. I can send screenshots of the file set up and such but sending the project is not a thing I can do.