Test webhook from gitlab's GUI, But failed

Hi All,

I would like to use Webhook for make new issue from ZABBIX-server first time.

I am using self hosted gitlab on cloud.
First, I made token with all scopes are checked.
and then I made Webhook using the token.

If I will test from GUI, gitlab respond with "Hook executed successfully but returned HTTP 404 "
I set URL like this.

Do you have any good idea for this?
Best regards.