Odd physics & glitching when adding scale to spawned actor


If I drag this simple mesh into my level, scale it up & rotate it it rolls down a hill no problem:

When I try to spawn the same thing via the level blueprint it either glitches through the floor or ricochets wildly into orbit.
I’m not sure why.
If I do the same thing with say, a ue4 sphere, there’s no problem.

Can’t see what I doing wrong.

Been playing around.
If I scale it up 100x (~50m tall tire) before importing there seems to be no problem, even after applying scale & rotation to increase again.

FBX’s attached.