These are very strange preferences probably happening by accident. All using the Android APP using the file browser option on my phone I am not talking about using the library. 1) "Back" has preference over "Cover, Folder, Front" If "Back" is cached at all it should have the lowest preference. As a bypass move the back.jpg files to an Art folder which solves this. 2) Folder.jpg shows correctly on the album when playing but nothing is shown browsing the directory. Did not find the root cause for this yet. Some albums have this. I guess there is some cache (not library) somewhere which isn't updated when the cover is added later. 3) The folder browsing displays the wrong image but the correct folder.jpg is used when playing. Some albums have this. Likely the same reason as the previous case but here the cover was replaced not added. To know: 1) "Cover" has preference over "Folder" which is fine for me. 2) All tried after a full library delete and new scan. I don't get the impression this matters at all.
Hmm, isn't it that the system searches for the files alphabetically, hence Cover comes before Folder; and Back even before Cover? Renaming the files properly should then work without any software intervention. albumart-01-front.jpg albumart-02-back.jpg should be enough, as the difference in sorting is already at 01 / 02 provided the system does no search ONLY for specific file names, instead of the very first image in the folder, which my fix assumes...
I think it's cause Back is alphabetical before the others. Also why not burn the correct image into the metadata? Keep the jpgs but burn the front cover into the files? I understand your issue but it seems like an impossible task to accommodate all different ways of naming images. Burning them into your files would most likely take precedence and fix the issue. And it would be the right thing to do as most files, even FLAC containers support burning images
Yes will try tagging to see what that does to it. But updating just adding a correct cover.jpg file to the album folder is far quicker and easier to do.
There are applications like mp3tag for free where you just tag them after you place them and you're done. mp3tag doesn't only work on mp3s, btw. it's a one and done operation and you never have to think about it again. I always check if there's anything burned in and if not, I burn the cover in myself.