How do I fix thousands of missing files which PSE 2018 thinks are on /Volumes/Recovery/... ?

I have PSE 2018 on Mac.

I'm trying to upgrade to PSE 2020, but before I do that I want to make sure the catalog is healthy.

I ran the "Reconnect missing files" tool and worryingly it found 100s of missing files.

The "original location" it displays for all the files is "/Volumes/Recovery/X/Y/Z" where X/Y/Z is the actual path to the files. So for example it says the original location is /Volumes/Recovery/users/ben/psamac/104APPLE/IMG_4384.JPG and the actual file is happily sitting in /users/ben/psamac/104APPLE/IMG_4384.JPG

So all the files are there, but somehow the organiser has become confused and thinks they should be on the recovery partition.

But I don't even have a recovery partition

Is there a way I can update the PSE database to point to the correct location of all the files?

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I tried using the reconnect missing files tool, but it has a strange bug where it's popping up the same dialog box literally thousands of times telling me every file which it hasn't reconnected. After browsing to a folder with some missing files, it says "File ... was not connected to ...". I click ok, and then it pops up again with a different file name. It's working through an entire folder of 1500 files. I have about 1000 folders. So I'm worried I might have to manually click Ok 1.5 million times if I try to use the missing files tool!! I think I'm going to have to Force Quit the application, but I'm worried that will corrupt the catalog more. Any advice appreciated!