There are 20+ pending tests on that test location / browser (Dulles, VA, iPhone 8 iOS 11) that hasn’t moved for several hours.
I’m seeing ~14 tests and the agent last picked up work less than a minute ago: WebPageTest - Location Status
Could be there was a really slow test in the queue (9 runs, first and repeat view can take quite a while) but nothing looks wrong with the agent itself.