@KatastrophicSim Somewhere else as travelling to another lot ?
To me sounds there's two issues you're seeing:
1. Not owed books can't be read to children (happens at libraries and on vacation). This is totally inconsistent cause you can read toddlers book just fine as well as adult books that don't belong to you. I do think it might have something to do with the way the interactions appears (only in inventory) while toddler books can be read from the bookcase itself.
I don't know if this is considered a bug by the devs or not.
2. Books becoming unowned for whatever reason. That def shouldn't happen but it would be good to know what interactions leads to that state. Moving houses could be a reason (cause moving and inventory have multiple issues). Maybe travelling with books in your inventory ?
So, bottom line, if you can find out what exactly makes them unowned for you, that would be great info and if you can also confirm that the are infact unowned (the put into inventory interaction will be greyed out and tool tip blabla doesn't own the book will appear) when you can't read them anymore, that would also be interesting info.
Not trying to give you a hard time here, just trying to figure out with what we're dealing here and what could be causing it (especially as I wasn't able to duplicate the second issue)
Going to mark this as needs input for now (for the second issue) to see if anyone else has issue with the read to interaction dropping from books. (Issue Nr. 2).
For the first one, I'll try get some official info