When checking the schedule and history in the administration console for workflows scheduled to run it shows that the workflows are running.
For example here is a workflow that runs every hour throughout the day and the last time it ran was supposed to be at 11am this morning (about 30 mins ago)
However if we view workflow history in the designer, we see there is no instance showing the workflow ran. The one instance from 8:52 was a manual run because the customer needed to get the workflow going at least once today as none of their scheduled workflows are running
Version 12.0.2503.2695