Looks like that fix applied in 7.18 hasn't worked as intended, or Qt threw yet another spanner in to the works, see
https://github.com/kovidgoyal/calibr...ad56d160f9bbcb
Basically if the cells of the Nth book in the list are being edited when Tab is pressed to go into next cell the focus shifts to the first book in the list and it sometimes gives focus to a seemingly random cell for that book… on one occasion it popped the long text edit for my Location column.
And, if the DOCX in that first book is open in Word the "File in use" error handler kicks in.
I tested Windows portable versions 7.15, 7.16, 7.17, 7.18, 7.21.101 and 7.23 - the first two were okay, the rest have the problem.
I'll raise a bug report. Done ==>>
https://bugs.launchpad.net/calibre/+bug/2092643
BR