When a new user is created in ASC, this must be done while logged in as the SA user(or with equivalent database rights). If this is carried out while logged in as a non-admin user, the permissions and user mappings in SQL for the new user will not be properly created, and will need to be manually added as follows:
In SQL Management Studio, expand the main Security node (the main one for the SQL instance, not the one under the database itself)
Expand the Logins node.
Find the affected user, right-click it, and click Properties.
Click User Mapping.
Check the Map box against the AA_ACCESS_REPORTS database in the top section of the screen.
In the lower section, check the db_owner box.
Repeat steps 5 and 6 for the AA_ACCESS_USER_MANAGEMENT database and any ASC databases.
Click OK to commit the changes.