Invalid Scope: psc-discrepancy-reports.write-full

I am testing some integrations with the PSC API in the sandbox environment.

I have trouble when I am trying to request an auth code using the two scopes (the ones needed for creating a report):

When I submit request with both scopes combined (see below for the exact string I am using, it is space-separated) I get error=invalid_scope

I am able to successfully get an auth code for just /user/ however /psc-discrepancy-reports.write-full by itself also gives error=invalid_scope.

Additional information:
I have created a sandbox user and I can login successfully as an end-user (for the scope).