Oh wow that's a cute bug haha unfortunately I have to fix that ;(
I've been trying for a while to replicate the bug but I can't get it myself. In that time I found and fixed two bugs related to beds, not related to the one you mention, so at least is something.
This bed, you have it from an old save file? I made some changes in this patch in relation to constructions, so maybe that's what is happening, that's my main theory right now.