Random cover imag sometimes doesn't work

Hi,

Some albums published via Lightroom don’t get a random cover image. I have to select one and then that one is actually shown. Switching back to random gives a blanc again

can you post a link to an album that shows problem?

Both “Workd War II” and “France” are album sets. Images are not published to album sets, therefore there are no thumbnails published to the thumbnails/ folder to be drawn from.
(random thumbnails for albums are drawn from an album’s thumbnails folder)
If you want random thumbnails for those sets, then export some images from Lightroom at the needed size and upload them via FTP to each set’s thumbnails/ folder.

Ah ok. So thumbnails do not show up higher than their own album. Clear, tnx.

Correct. That’s why Matt and Ben created a way to assign a specific thumbnail to a set.