HOWEVER as a side step, some roof slabs can be selected with the magnet (spacebar+click) and some cannot.
The ones that can be selected with the magnet have a cover fill.
The ones that can't don't.
It can be an empty will with a transparent background, so you can't see it, but you can still select it with the magnet.
One of the forum moderators.
Versions 6.5 to 25
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Dell Precision 3510 - i7 6820HQ @ 2.70GHz, 16GB RAM, AMD FirePro W5130M, Windows 10