when did you setup the schedule? Based on your screenprint, it looks like it will kickoff next Monday. Wednesday @ 12:15am already happened after your post.
Also, do you have backgrounders? You need at least 1 to have refreshes kickoff.
Here are some confirmations,
Have you got any alert on Tableau Server?
Is Backgrounder service running normally?
What do the administrative views related with extract task look like?
(Background Tasks for Extracts, Background Task Delays)