The plugin doesn't seem to accept an HTTPS URL for the ZAP API. The "ZAP API URL" field note reads: "The fully qualified domain name (FQDN) with out the protocol. (Eg. zap.example.com)" and attempting to add "https://" as a prefix causes the scan to fail entirely with a network timeout. If the API exposes HTTP as well as HTTPS then it is accessed over tcp/80 only (confirmed in Wireshark).

Is there any way to require HTTPS for the ZAP API URL?

Thanks.