Dropsync Not Recognising Files

[Rod McInnes]

I have Dropsync3 set up on a MacBookPro running Mac OS Sierra, and have been running it for some years with an iMac running Sierra and then High Sierra. 

I have just replaced the iMac with a new iMac running Catalina.

I have setup a new Sync in Dropsync but I get very different results. 

Dropsync can see the paired folders on each machine and compare them. I have set file sharing preferences to give me access, and to the extent that I can add the folder to Dropsync from Finder, that seems to be correct. The paired folders should be near identical, having being synced across machines just before the old iMac backup in TimeMachine was imported into the new machine. 

However, I find there are 80,000 files requiring syncing in the Dropsync Preview and that the Affected items list starts with files that I can see are definitely on both machines, and which therefore shouldn't be affected items. My concern is that if I start the sync, I'll end up with not a sync, but a duplicate of my MBP folder on the iMac. 

I repeated this a couple of ways - first using my old folder pair from before the new iMac and then creating a new folder pair, but both ways have the same result. 

The iMac side of the Dropsync panel doesn't list any files, just the folder to be synced, so I wonder whether there is some Catalina security option locking Dropsync out of the file identities there. 

Any ideas on what I should do?