No lightmaps on geometry objects?

So here I really don’t know why there are no lightmaps after building…

Here’s the preview

Here’s what it looks like after clicking build

Much appreciated for some tips or solutions

I use a box brush for the floor

nvm I solved it, it turned out that the value I set for the box brush’s lightmap res was too high(like 512). Setting it to 4 got it solved.