[stumped]

I hate having to uninstall mantano/bookari because all themes are then lost & there is no way to back them up beforehand , they are not stored in the .db with everything else. That is also why I am nervous about testing rollback via local app backup, I spent ages getting theme colours just right and there's not way to re-enter as digital values -

I have never seen the alleged "open with... " option in the bookshelf but to be fair I only have epub2 books, maybe it is only supposed to show up on an epub3

and FWIW i really dislike the way that some new releases introduce bugs not previously present e.g. for me 3.07 broke the custom text colours in my themes , they were fine in 3.01 - 3.06 , & the bug was fixed in 3.09 so broken for 2 - 3 weeks - and for you 3.10/11 has broken an epub3 feature - these things need to be caught in QA before release to store