I’ve been testing some various paths/files with the user and I’ve narrowed down the issue to being just Bluebeam Revu not supporting the registry modification for 256 characters. Bluebeam themselves state that the program doesn’t support file names over 256 characters - and the files work when opened with other pdf readers/editors.
The odd part seems to come from how it gets to the folder - if it’s never uploaded/synced/touched outside of getting a long name, Bluebeam seems to fairly consistently be able to open the file - but once Google Drive/procore/odrive/whatever touch it, it’s done for.
This can be considered resolved since the issue is directly related to Bluebeam “While a recent Windows update has made it possible to raise file path character limits, Revu is currently not compatible with file paths longer than 260 characters.”: Studio Error: "The Project file path is too long."