Unable to select Authenticator in Create ACME Certificate form

I created an ACME Authenticator named "AWS", with Route53 selected and my Access ID/Secret keys filled in. These keys are already working using acme.sh.

Then I created a CSR with the CN set to my.fqdn (and also tried a different CSR with subjectAltName=DNS:my.fqdn). I click on the dots and choose "Create ACME Certificate".

In that form no Authenticator shows up, and in the console there's the error "Cannot find control with name: 'dns_mapping-my.fqdn'" and then hundreds of "TypeError: Cannot read property 'dirty' of undefined at Object.updateDirectives" errors.

Also, sometimes the Save/Cancel buttons appear under the form and sometimes they don't.