I have seen this before if the library you are opening is in a cloud storage location like Dropbox or the iCloud. You can check if your system is set to use the iCloud for the Desktop and Documents folder:
- Click on the Apple icon in the upper left corner of your Mac’s screen.
- Select System Preferences… from the dropdown menu.
- Click on iCloud in the Preferences window.
- Click on Options next to iCloud Drive.
- See if the box next to Desktop & Documents Folders is checked.
If that option is checked and your library is in either of those locations or a subfolder of them, that can cause this to occur. I would suggest clicking the Go menu and selecting Home. Create a new folder under your Home folder. Next, see if you can repair your library and save the new copy to that new folder. You can try the Standard Recovery steps found here: