Hallo Andy,
thank you for your information about the non-existence of the problem in your environment. I'm doubtful whether the problem is specific to my installation or a general one. I have about 2000 coverarts so that it is rather time consuming following your proposal ("I would try to temporarly move them in a different folder and move them back step-by-step until error occurs."). What I just did is to restore an old backup and the problem persists.
Hm?
klassikmann