400 error when submitting issues form

I’ve created an issues form here: fd/bug_report.yaml at 5fbfdfadb82763199127427bc88c24d74aeb3f03 · sharkdp/fd · GitHub

And for testing I set it up here as well. When trying to submit the form (in both projects) Github immediately returns a 400 with no content or error message.

Is this a known issue?