Reimporting a static mesh will cause some Static Mesh Editor values to be reset back to defaults.
This was reported as JIRA UE-22205 back in 4.10 and was marked fix in 4.12. However, I wasn't able to verify it was fixed because reimporting crashes the editor in 4.12.
Static Mesh property 'Allow CPUAccess' un-ticks itself when you re-import the mesh.
It's never a problem in-editor if its un-ticked, but in cooked builds this really messes up our stuff.
Results: The 2 values enabled will be reset back to default values when the static mesh is reimported
Expected: For all values to be maintained on reimport
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-46829 in the post.