Workforce Rule Failing for Unknown Reason

Summary:

Rule and Ruleset failing for unknown reason

Content (please ensure you mask any confidential information):

I have a ruleset in workforce that is scheduled in jobs to run nightly. This has been running for months with no issues. On the 7th of this month, it failed. When I looked at the jobs console, the reason is listed as unknown. Looking at the run time, it is taking about 2 hours to list at failed. It also gets hung up on one specific rule. There were no recent changes to the rule and I ran it in the test environment and it processed normally.