I have APIM with custom domain and NSG set up to allow only access (inbound) from Front Door. My front door is set up and all is working fine. I can access the developer portal. However I cannot access the developer portal designer (the 'Developer Portal' button on the APIM overview page). When I remove NSG the button is working - taking me to the developer portal designer, but going via FD always gets me to developer portal home page, not designer:
This is a home page of the Developer portal - an automatically generated....
I also tried to set up Azure AD in Identities tab, adding my FD domain to app registration return url, but the effect is the same.
Any idea how I can launch the designer via FD?