[Shadowjack]

I have been using Calibre for years and its great, but I have recently had a problem. I have two books that for some reason are not showing up in their collection. When I view them in the Calibre library they look fine but when I upload them to my prs-505 they don't show up in their appropriate collection. When I view my reader from Calibre the tag field is blank for these two books. I have tried deleting the books from my reader and reloading them but that hasn't helped. I even tried removing every book belonging to the same collection I was adding to and reloading and that didn't help. The same two books still didn't show up. Suggestions?

Calibre v6.47
Sony prs-505