Static mesh changing its mobility from static to movable.Is this a bug?

I dont know if this is a bug. I have a static mesh, a floor. I have it placed at 40 on the z axis with its mobility set to static. Once I play in editor it moves to 65 and its mobility changes to movable. I’ve tried reimporting it, no difference. I haven’t tried deleting it and then import it again, prob try that next.
Kinda at a loss to why its moving like this, I did a bit of housekeeping moving files into folders and dont know if that might’ve screwed it up.


So I ended up deleting it and that fixed it,