I have same version and :USER and :PASSWORD works fine. Having said that we don't have SSO.

Try to login in essbase from EAS with the same user. see if the user has all required essbase access.

You can also test this in your RPD....

right click on dimension ...and select view members.

select your connection pool and hit select. This window will come up.

provide user and password in the value field. This will probably bypass SSO agent. Check what happens. Also check from Administrator -> Manage Sessions page to find out if the user logged in is the correct user.

Thank You

Arijit

I verified and sorry my version is  12.2.1.2 not 3. I think you may need to talk to Oracle support if same connection works for 12.2.1.2.