Hello and thanks!
Just for fun I also downloaded slope but neither slope nor hillshade was visible even after multiple times checking the buttons and sliders.
But then i discovered the cause of the problem:
I had the data storage folder set to my external sd-card.
After setting that to the internal storage and letting osmand move all files it worked perfect!
Without any other changes hillshade works well on internal storage and doesn't on external.
There seems to be a problem with android 11 and the external sd-card. Osmand had no problem with maps on the ext. sd-card, only with hillshade and slope.
I tested this behaviour on two different Samsung S4 with lineageos 18.1 and two different sd-cards.
I hope this can be fixed in future updates.
Storage on ext. sd-card is a must for osmand users with large collection of maps.