A web server can be configured to listen on a very particular Server Name (SNI), not listens with an IP address. Zabbix offers a network discovery to find servers that listen on port 443.

If a host listens behind SNI, the resource will not be found by a network discovery.

Kindly allow to optionally conduct a reverse lookup for the IP address, then rescan the object with a server name, to successfully identify an HTTPS resource.