I have a moderately large catalog of 200k+ images on an NVMe drive in my Mac Pro 5,1 running Mojave. A 'reintegration needed' message came up and when I ran it it was still going after 8 hours so I left it overnight. The next day when I came back the Mac had crashed. I tried again and it reached 100% in about 20 minutes but it stuck there without finishing. Activity monitor showed a pm-task using about 100% CPU. After an hour I quit & tried again after optimising the SQL first. The SQL opt. ran OK but after that the reintegration again stuck at 100%. I left it about 8 hours this time, Activity Monitor again showing PM taking ~100%.
What can I do?
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Edit an hour or two later
I tried again, the reintegration stuck at 100% as previously and I quit after an hour. This time, on opening the catalog, the 'maintenance needed' warning was cleared. This no longer seems urgent but I'd still like to understand the problem and know what to do if it recurs.