Sorting A-Z causes new books to not show up, and multilingual issue

Hello!
I have a problem in our OMP 3.3.0.8. I noticed a problem in one of our series, when I added a new book to it, it would not show up in the list on the series page. The series was set to sort books from A-Z, but when I changed the sorting to “newest first”, the new book appeared in the list. The old books were added before upgrade to the current version (from 3.1.2.4).

Today I found that the exact same goes for categories. I also found that when sorting from A-Z, none of the books show up when changing language from English to Swedish (we have both languages in our platform). Instead it says ##catalog.noTitlesSection##.

Anyone have any ideas about what could be causing this? Bug?

Best regards,
Magnus A