For now, try this:
- Turn off sync on each device, and choose to remove the data
- Wait 10 minutes
- Go into your Dropbox folder on the Mac. Look in Apps.
- Find the Agenda folder in Apps, and drag it to the trash
- Wait 30 minutes for that to propagate to Dropbox
- Start sync on one device (eg Mac). Let it just run for an hour or so
- Now start sync on another device. Again, be prepared to wait
I tried to do the “full unsync and reload” steps found here: Dropbox sync sporadic and one way
Seems to have done the trick!