HTTP/2 Dependency Graph blank sometimes?

Lately, WPT results have sometimes ended up with a blank white page when I click the View HTTP/2 Dependency Graph? Example result blog.centminmod.com...ifornia, USA - EC2 - WebPageTest Details and the View HTTP/2 Dependency Graph link.

My Wordpress blog is behind Cloudflare but I have HTTP/3 disabled so they site is served via HTTP/2.