I have the same issue, as I move to each new page of albums, the images are gone, will eventually load. After a restart all images are gone again.
I am running Roon on a PC, cover art cache is set to 2048MB - no change
I have disconnected and reconnected - no change
@Lars_Hansen1 mine is slightly different. After restarting closing both, Roon and RoonServer (in no particular order) all artwork loads normally. Does this work if the same process is followed?