I have a database synced via Dropbox. Inexplicably, it seems to have stopped syncing some time ago from my laptop (also accessed from a desktop). Now when I try to re-establish the sync from the laptop, it refuses: namely, in the Sync panel in Preferences, the database in question says “Not yet synchronized, upload database.” When I select synchronize (in any of the multiple places one can choose that) I get a brief flurry of activity, then nothing happens.
I do not understand how a database just stops syncing without any notification to the user. I also do not understand why it now refuses to sync.