Hi Martin,
I just did some tests on my server and I am facing the same issue.
There seems to be a synchronization problem between CA SOI users and CA EEM.
When adding a user in CA SOI to a specific group, this is not reflected in CA EEM properly.
The user gets access to CA SOI, but in order to get access to USM Webview, the user must be member of the group in CA EEM, which is missing.
I manually added the user to the Application group "Administrators" in CA EEM, and then this user also got access to USM Webview.
I recommend you open a CA Support issue to follow up on this.
If you let me know the issue number (michael.boehm@ca.com) I will follow up internally.
MichaelBoehm