I didn’t use any values in the URL pattern, just pasted the Losant webhook into the field. I just put the content as json in the body like you have in your post. In Sigfox I use the HTTP method POST, click the Send SNI box for SSL, keep header value fields blank and set content type to application/json. I’ve never messed with the header/value fields in the SigFox backend, but I’ve never used them for anything with SF that I have done. I’m also not doing any authentication in my webhook, but that might be something I want to explore sometime soon.
Hopefully that helps. Just so you know I’m just another Losant user, so working to learn more about this platform as I go!