Steps to reproduce
Hi, username! > My Bookmarks > Bookmark External Work
Fill in all required information except one field, e.g. Title
Choose a Rating other than the default, e.g. Teen And Up Audiences
Check a Category, e.g. Gen
Add any other information you like
The bookmark does not save and I am prompted to correct errors. However, the Category and Rating I chose are no longer selected.
What should happen
The Category and Rating you selected should stay selected.
I started to make a new external work bookmark, and I left out the creator. When I submitted, it gave an error, and the category, rating, and everything else I had entered (fandom, notes, title, URL) were still there.
I tried to create a new external work bookmark with just a fandom, a rating (M) and 2 categories (M/M, Multi). I got validation errors for all the missing fields (title, creator, URL) but my fandom, rating, and categories stuck around. Looks good.