[SalesForce] Time based workflow queue is getting emptied

Couple of days ago I viewed a queue of Time-Based Workflow rules which notify a specific person (by creating tasks and emailing), but today I found this list is empty. This person mentioned that she turned off all notifications. How is that possible that it emptied workflow queue? I don't remember reading about it in any documentation. Is there a way to roll back changes?

UPDATE #1:

Workflow rules are active and were not changed in the last couple of days.

UPDATE #2:

Yesterday I fixed my rules and using apex triggered WFR to re-evaluate existing records and had my queue populated again… BUT I came in today and it's empty again. How is it possible?

UPDATE #3:

I found out that a scheduled apex class was causing an error and for some reason it cleared all WFR. Now it's fixed.

Best Answer

Are you sure it's actually triggering? It might be helpful to have a temporary checkbox which gets set as an immediate action to confirm the WFR is triggering. Also it's possible the record not longer matches the criteria, maybe someone has done a mass update?

Note:

Will the pending actions in the queue ALWAYS fire? No. Time-dependent actions remain in the workflow queue until processed or the rule criteria for the workflow rule is evaluated as false. If a record no longer matches the rule criteria when the rule is evaluated, Salesforce removes the time-dependent actions queued for that record.

For example, an opportunity workflow rule may specify: A criteria set to "Opportunity: Status not equals to Closed Won, Closed Lost." An associated time-dependent action with a time trigger set to seven days before the opportunity close date. If a record that matches the criteria is created on July 1st and the Close Date is set to July 30th, the time-dependent action is scheduled for July 23rd. However, if the opportunity is set to "Closed Won" or "Closed Lost" before July 23rd, the time-dependent action is automatically removed from the queue.

Taken from: https://help.salesforce.com/HTViewSolution?id=000005245