I was going through the same problem and I reseted my computer doing P-RAM. Opened the hard drive, duplicated the project and it worked!
Not sure if this is the best solution but it just worked for me. It has been happening a lot lately but this time my temporary file didn’t have all the changes I made, so I really had to try hard to recuperate this one.
Thanks for all your help always!
Eliana Alvarez
Filmmaker/Cinematographer
https://www.elianaalvarez.com