Fetch and Lock not retrieving available External Tasks

We have external tasks waiting to be fetched and the Rest API is returning no results. No errors in the Camunda logs. Changing the priority on the tasks from 0 to 1 causes them to be fetched.

What might cause this?

@Bill_Powell , Priority 0 is the lower priority.

  /** indication of how important/urgent this task is with a number between
   * 0 and 100 where higher values mean a higher priority and lower values mean
   * lower priority: [0..19] lowest, [20..39] low, [40..59] normal, [60..79] high
   * [80..100] highest */
	void setPriority(int priority);

Have you set this producePrioritizedJobs = false in process engine configuration?

Thanks, I don’t think we have producePrioritizedJobs = false set unless that is a default. Our system has been in production for a couple of years and all tasks are 0. This particular situation has never occurred before.