Bruji

Book covers I have added to the collection go missing. I will re-add the images and they then disappear again. It seems to be the same books each time as well.
I add my own covers that are high resolution and will match the edition I have added to the collection. I am thinking they may disappear during updates to the app but will need to track that on the next one.

There are some hidden menu tasks that you can perform:
Hold down the Option key and click on the main Help menu and select - each in turn: 'Verify Database', 'Remove Orphaned Covers' and 'Clean Duplicates in Fields' these may not solve your problems but it wont hurt either.

Also have a read of this Topic: Pedia Maintenance Practices

I ended up figuring out my issue. I use iCloud and the folder that holds the covers is in an iCloud folder. For whatever reason the missing covers were not downloaded locally. Once I downloaded them they showed fine.

Great to hear plus that is a handy piece of advice for trouble shooting for others.