Turns out the change I made to the reports (theoretically to modernize the way they were handled) was completely incompatible with the memory-saving measures we've put in place in the turn scripts. So not only have I reversed the changes I just made, I've also converted all the region reports that were already using that more modern method (some dating back months or years) back to the old method.
This should fix some frustrating missing reports that people have noticed in the past, as well.