[ownedbycats]

Created a fresh test library for replication and was able to repeat results even in a portable Calibre with only Reading List and View Manager. So here it is.

Steps to replicate. For this you'll want both Reading List and View Manager installed.

1. Switch to the "On Device" view. This will let you see all the available books and the reading list series column.
2. Remove one of the books from the "To Be Read" list.
3. Press whatever key is assigned for "Re-apply current sort." I think by default it's F5. Alternately just re-apply the current view.
4. The book should end up getting stuck at the bottom of the list.

It remains there even when switching to Default or Fanfiction views (depending on which book you use for testing). It resolves if you remove "Reading List" from the sort.