Regarding the issue with artwork in playlists, I came across this script here today:
View attachment 2598993
I tried it with a few playlists and it works as described. The script creates a new playlist with covers. The old playlist can then be deleted. Works perfectly for me!
Today I also solved the issue that I had with the Remote App since years. It is now playing complete albums and playlists again. Sometimes a cold, rainy day has its advantages. (My Ipad was not connected as a remote. I didn't know that was necessary. It worked .... until it did not. Never came across this easy solution.)