Running test with JavaScript disabled causes failure

I’m trying to test the performance of my website ( with JavaScript disabled. I’m going into Advanced Settings > Advanced and choosing “Disable JavaScript”. When I do this it takes several minutes and then the results say:

Test Error: Page Load Timeout

But when I view the page in a browser with JS disabled it loads fine. If I do a webpagetest with JavaScript enabled it completes in a few seconds and the result appears correct.