I was trying to use the single-signin APIM api's i.e "/generateSsoUrl" for generating the redirect url and using it to sign in into the developer portal. I was able to login using the api, but after logging in we were not able to click/navigate to any page. The user is not "really" logged in - Just the menu thinks the user is logged in and When i click any button on the Profile Menu, the user is either redirected to the /login page or is logged out.
I generated the redirect url using this: https://learn.microsoft.com/en-us/rest/api/apimanagement/2020-12-01/user/generate-sso-url
The redirect url generated by the above(witch is the legacy portal by the way): https://(my-service-name).portal.azure-api.net/signin-sso?token=xyz...
and if we tries to replace "portal" with "developer" and encode the token as well, then still the above behaviour is replicated.
Also, everything is working with the deprecated/legacy portal.