With these versions of macOS Final Cut Pro X users are experiencing an error with FCPX reporting the storage location is not available and changes cannot be saved.
This issue has been reported to the macOS Catalina team at Apple and has been followed closely by the Final Cut Pro X and LumaForge teams.
Please copy your Final Cut Pro X Libraries to an SMB share on the Jellyfish. There are no known issues with SMB shares at this time. You can continue storing your media on your NFS shares so you don't have to perform large copies.
If you prefer to have everything in one place and you decide to copy, please make sure you have enough room on your Jellyfish. We advise you to use the Hedge application to available through the Resources page in the Jellyfish connect app for transferring your data from one share to the other.
We are sorry for the inconvenience and we are hoping the issue will get resolved soon.