Question about Inventory Managers

We had a receipt transaction get stuck last week.  It looked like it had completed, but inventory was not incremented. Upon reviewing pending inventory transactions, the transaction was shown to be pending in On-Line Processing Mode. There was no error message on the pending transaction and submitting it did not remove its pending status.  Eventually, we tried launching the Material Transaction Manager and the Move Transaction Manager.  This did the trick, though we don't know why they suddenly stopped running in the first place.  They are setup to run every 5 min. like the Cost Manager, which was still running.