strange shadow 4.12.4 (simple box)

Hi, I’m getting this strange shadow

The only things in this scene are the floor and the box - the light is a spotlight obviously, but I get the same shadow with a directional light… I’m not really sure where to start troubleshooting this

Here’s a close up…

and this is the editor preview without lighting being built, which is what you would expect to see (and what i’d like)…

The spotlight is currently set to stationary. When I switch the spotlight to static and build lighting I loose all shadows from the box and the penumbra falloff from the light gets all blotchy and gross looking.

Both the floor and box are static objects set to cast shadows and they have unwrapped uvs

Thanks for any help

I increased the light map res for the actual floor geo and the problem is fixed