Why is my physics actor doing this?

I have a propane tank and have set up the blueprint with a physics thruster. However it collides rather weirdly with the floor. Collision has been set up on the static mesh to block all and has its own simple collision. I have attached a video to show my problem.

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Not sure if it is the same for you, but this is how I solved a similar issue: I had this object when I set use complex as simple collision in the static mesh editor. Make sure you use simple and a capsule collider.