There may be an area with an unfinished conversation or mission, so check all of your previously-discovered areas. There may be an important conversation or task that was missed.

This may also be caused by an account conflict if you play on two devices simultaneously.  We recommend playing exclusively on one device or the other.

For example if one starts a job on device A, finishes it on device B and then goes back to device A before the two devices have time to sync, quests may appear to be unfinished even though they have been completed on the other device.