Failed to fetch – Can't use test

[alexstyl]

Description

I am trying to use the page test but when I click Start Testing button, nothing happens.

I do see this log in the js console in my browser though:

Uncaught (in promise) TypeError: Failed to fetch
    at n (frame_ant.js:2:15571)
    at window.fetch (frame_ant.js:2:15723)
    at WPTForm.sendTestSubmission ((index):550:22)
    at WPTForm.handleFormSubmit ((index):519:9)

Steps to reproduce

Visit https://www.webpagetest.org/, enter https://composables.com/ to the field and hit Start testing.

Expected result

For the test to run? No idea what happens next. I was recommended your site via ChatGPT.

Actual result

Nothing happens.