Blotchy Lightmaps (progressive Lightmapper)

I'm getting these weird patches every time I bake my scene.

The project was fine before I added the furniture, and it only seems to affect these two areas. Played around with render settings but nothing seems to be helping. Generate lightmap UVs is turned on for both the floor and the furniture.

Any help would be greatly appreciated. This has happened on another much smaller recent job too, but I don't remember ever having this issue in the past.

Using Unity Pro 2019.3.4