(due to a recent incident- I decided I should post a small journal about it for future reference and to help anyone else that may end up having this issue)
How to troubleshoot corrupted files in CSP
While the the corrupted file itself can't be saved, there's a way to find a backup of the file. So your work's not all lost.
Find the CELSYS_EN folder within your documents folder, go to CLIPStudioPaintData and go to DocumentBackup. Find the most recent/prior version of the file you were working on. Open that up and it should work. 'Save As' this file and save it elsewhere.
Note: I'm using Windows, but I assume it should be the same location for Macs