File thumbnails in finder

I found these commands

qlmanage -r
qlmanage -r cache

in another thread that was regarding quicklook.
I am assuming its touching on the same issue though.
After running those i did a reboot.

Seemingly this caused more thumbnails now to generate
but still couldn’t do the entire folder.

Apparently it always crashes halfway.
It would be neat to have reliable thumbnails

can you send me some files that don’t get a thumbnail?

as the thumbnails get rendered for specific sizes.
and once the thing has crashed and i can resize the thumbsize none get rendert
so it seems arbitrary.
in other words all/any files suffer from no thumbnail.

depending if i start viewing the folder from the top or the bottom
i get those thumbnails and then none