Enabling OAuth setup in OIC gen3 to connect to Fusion instead of Basic Auth

Dear Engineers,

We have set up a fusion connection in OIC gen3 towards Saas/fusion using Oauth.

The set up was done according to Oracle documentation.

For our DEV environemnet and TEST it is working fine. When clicking provide consent it redirects to Saas, you login , test and save connection.

However, when doing this in our ACC and PROD environment, when clicking Provide consent it redirects us to an IDCS page instead of the fusion page. Which should not be the case. We have checked many times the applications (client and resource app) created in IDCS fusion and it has the same configuration as the ones for DEV and TEST.