I truly believe that your solution works. The main question about the cover issue for me is: "Why I must do a copy, delete from iCoud and re-import at all to change the album art? Should'nt be an update of covers as simple works as the rename of an artist or title? All changes in the iTunes library are simple and will be synchronized almost instantly through all libraries on different devices - only cover artwork changes requires ugly roundtrips!"
PS: I double check what kind of covers do not appear in the iPhone5 cover flow view - all covers have a low resolution (300x298 around this area). When I replace them with the "extensive" solution you described the covers will show up. And by the way, there is no restriction to an upper cover size - I have also covers with (>1000 x >1000) those albums show stunning cover art, at the Mac and also at my iPhone.
PPS: As long as it do not work in a simple expected way I considered replacing of cover art as BUGGY - I would say: "unaccaptable".
Call it bad programming on Apple's part.
The same issue existed with MobileMe syncing, nicknamed chasing the tail.
Obviously iCloud has the priority, so the ONLY way to update older artwork, is to delete it from Match/iCloud.
What annoys me is that I lose the DATE ADDED data which is what I base my smart playlists on.
Using DATE MODIFIED has its own issues.
The upside is that the new art matches the iPad and Retina display resolution.
All pre-iPad art was smaller.
I remember when the first iPod (photo) looked fine with thumbnails.
More annoying is Apple's constant allowing publishers to remove and reupload their music, which causes mismatches with original data.
sorry to interfere your enthusiasm but the only thing you made is whether to add an artwork for an album not containing album artwork yet - then your are a lucky one: iCloud add your new cover. But when your album already had an album artwork the only thing you made is a local replacement in the local cache "~/Music/iTunes/Album\ Artwork/". Just check your library at other devices or delete the local cache to recognize that iCould did not update your cover. This is what this thread is all about.
It is always best to ensure that all your Song metadata (including Artwork) is in order prior to loading into iCloud.
Removing the local and iCloud versions of a Song is straightforward.
Working with local Song file and iTunes Match switched off - you can adjust metadata as required.
Once content, sign-in to iTunes Store and start the iTunes Match process - the correct version will be made available in iCloud - note you may need to re-download from iCloud to force change on all devices.
Read my instructions above mate.
Hopefully soon the update to 11.0.1 or whatever where they said missing artwork will also include the fix for replacing artwork.
The engineers do know about this glitch, which is also causing Match to lose music.
Will keep pestering them.
iTunes 11 in general is frustrating especially the new search capabilities which have been really dumbed down and giving errors.
I want to revisit this issue now that iOS 7 and iTunes 11.1 have been released. With all the latest installs I was having changing artwork then noticing that it reverts to what is in itunes match, just as others have described in threads like this. So based on what I read on the threads I took the following steps to remedy the situation:
1. Delete the albums in question from iTunes and iCloud.
2. Turn off iTunes match.
3. Re-import the deleted albums to iTunes.
4. Correct the artwork.
5. Turn iTunes Match back on and allow it to re-upload the files.
Most people report that those steps fixed the problem, but with the latest software I now have a situation where the artwork is correct on my iMac in iTunes but wrong everywhere else (iPhone, iPad).
Still seems to be a bug. Does Apple read these threads?
Anyone have an idea?
Obviously not a priority for Apple.
They have fixed a few glitches that came with iTunes 11.
There are new issues, with workarounds.
As for cover art and match, it's all about matching metadata in Album Artist and caching.
The data must match the iTunes listing.
You must delete from iTunes and you may need to restart iTunes.
Reimport the song, and allow the art to populate. If there is no art, paste it in, and then allow the match.
It then should appear on your device.
There are some albums which refuse to play nice, for some reason.
key menu option: "Consolidate Files..."
I have been struggling with the same problem with artwork reverting for a few years now. I have just now discovered that if I right click on the album I am having problems with and choose: "Consolidate Files...", it finally seems to work. What's more, I can update the album in iTunes and watch it update in almost real time on my iPhone. It's amazing!
Here is the exact sequence I used:
1. Get info on a track in the album and "copy" (Cmd-C) the artwork you want, or have the artwork handy in the Finder.
2. Delete the artwork on the album. The easiest way is to right-click on the album and check the box next to the empty artwork box and select OK to close the info window.
3. Right-click on the album again, and choose "Consolidate Files...", then confirm your choice with the "Consolidate" button.
4. Now open the album info dialog again and paste (from the copy in #1) or drag the image from the Finder into the artwork box. If pasting, click on the emty artwork box first to make it active and then paste.
5. Close the info window with OK.
6. Finally, "Consolidate Files..." on the album again as in #3.
I'm not sure if all this is necessary, but it worked for me. Maybe some subset will also work. Also, there may be other causes for this problem, so I'm not sure if this solves all cases.
Hope it works for others.
Hmmm, I guess I spoke too soon. Unfortunately, after 4 days of fixed artwork, it actually reverted. Insane. Strange, as I just upgraded to Mavericks. I wonder if that reset something, I can't believe the old artwork is still floating out there in the cloud. Sorry for the red herring. Have to go back and waste some more time trying to figure it out again.
Another one of my albums which refused to display any art, has been resolved by logging out of match on my iPhone and then back in.
The consistent inconsistency by Apple software continues as the last time I logged out and in when switching to a new device, only 2 of the 3 holdouts appeared with corresponding cover art.
This while not the fault of Apple, but the content administrators initially due to inconsistent metadata which iMatch depends on, ultimately should be moderated by Apple.