WordPress site was unpacked from archive created on MAC OS to domain drectory.
There is a folder
_MACOSX inside domain directory and WordPress Toolkit detects files in this folder as broken WordPress instance.
It's a bug EXTWPTOOLK-1763 that will be fixed in a future Plesk updates.
- Login to Plesk
- Go to Domains > example.com > File Manager
- Just in case create a zip archive of _MACOSX folder and remove this folder
- Go to example.com > WordPress and Detach broken instance and then click on Scan.