Great workaround for those willing to try it.

Ideally, users shouldn't have to trust additional parties on top of Dropbox to sync notes reliably. See a similar sentiment here: Allan_Quartermain comments on What's a good free solution to syncing between Windows, Android, and Linux?

If this bug is on Dropbox's end, that should be clarified. If not, the Joplin team should still resolve it. Does the linked Github issue lack anything needed to start working on a solution?

Dropsync requires payment to sync more than one folder. Autosync requires payment after a 14-day free trial. Would established FOSS alternatives like Syncthing or others work for this purpose instead?