Syncing with Dropbox, hangs after 1st pass

Running DTP v3.04 on a desktop Mac (10.12.6) and a MacBook Pro (10.14.6). A single Dropbox syncstore is used to synchronize 7 different databases. The Mojave system has no problems, whereas the Sierra desktop (which is not compatible with Mojave) fails after synchronizing with one pass through all 7 databases. Typically this on the same database, but not necessarily so.

The symptom of failure is a continuing spinning circular icon. This only stops when the Dropbox location is unchecked in the Preferences: Sync window. DTP must then be quit, restarted and the Dropbox syncstore re-selected, at which point the synchronization takes places, hanging after the first pass. DTP remains useful during this and doesn’t freeze.

What process should I use to reset sync?

Please launch Apple’s Activity Monitor application (see Applications > Utilities), select DEVONthink 3 in the list of processes while the sync is hanging, choose the menu item View > Sample Process and send the result to cgrunenberg - at - Thanks in advance!