Krazykanuck, where do you store your Cover Art? (MC offers 3 location options).
My cover art is "In a specified folder" and is NOT stored in the audio file. The cover art images display perfectly, but Rebuild Thumbnails does not populate the Image Width and Image Height fields. I tested two libraries, no success.
But I first tried this with 20.0.49 when the fields were inadvertently hidden (unhidden in .50). Wondering if that did something to keep them hidden, that needs un-doing, I deleted the two fields from the library's folder. They were each 1KB, obviously no content. Then I ran Rebuild Thumbnails again. No change, the fields got recreated by MC, but again 1KB in size, no data in these fields.
Other than wondering about cover art location options, I have no clue how to make this work. Perhaps delete a cache somewhere?