Somehow a Frame Break was inserted at the beginning of every individual part in my file. Is there some setting that would’ve inadvertently caused this? Is there any easy way to delete all of these Frame Breaks at once without having to go into each individual part, select, and delete?
You will need to go into each part in turn, but thereafter you can trigger Unlock Format via the jump bar, which will be pretty quick. You can move to the next layout by typing Shift+Alt+], so it can be as quick as J, Return, Shift+Alt+]. Should take no more than a minute, even for a large-scale project.