Plot graphs are not displayed on WPT.org

Hey,

Thank you for the invaluable tool.

I have been running some tests on wpt.org since last 2-3 weeks. And on all tests, I do not see any graphs when on Test result data plots (graph_page_data.php).

I have checked this on Firefox 79, Chrome 85, Firefox Developement, Chrome Canary, as well as on latest Chrome/Brave on Android. Neither of these browsers shows any console errors.

Here are some reference tests:
https://webpagetest.org/result/200909_8N_1bb048bffd587ab727a22e2c0ed0a452/
https://webpagetest.org/result/200903_C5_7a9c7b055f07f306ab8aea995e457aea/