When I click Scrub Volume, does it display a status or results somewhere? It says "The scrub process has begun" at the top of the screen but then I don't see any other info about it, what the results are or what the status is if it's still ongoing.
You didn't say what version you are using, but 8.0.2 has a 'zpool status' icon to the right of your volume after you open up the Storage->View All Volumes on the left.