I have setup a transform rule to add a header to the request “X-Cloudflare-PSK” when the hostname equals a subdomain of Cloudflare hosted domain. The rule is to ensure that our API only gets severed on our domain rather than the service providers temporary domain.
It appears that Cloudflare is just not adding the transform rule to requests via the hostname - when I use postman to add the header to my request it all works fine!
The gateway looking at the inbound request is case sensitive but that should not be the problem.