When I test a target, it does not test successfully. When I open the Dev Tools in Chrome, I get a 500 error from:
Target tests can silently fail when calling a secure URL while the SSL Certificate is not trusted.
Please check that your SSL Certificate is trusted. You can enter your full url (include https) at DigiCert.com. If it is not trusted, you will need to resolve that issue.
For better error message, you may activate the target. Failures of an active target provide better error messages than those provided while testing.