From VCC14 onwards the user access to the webcenter including reporting, contact explorer and dashhboards is controlled by OLA (Object Level Authorization) in wich all rights for all users for all objects is defined. A specific report may depend on different objects so a user may need different rights to different object to be able to see a report.
When unexpected behaviour is found, logging can be used to find the reason for the strange behaviour. This WebCenter logging can be found in the WEB10_Log table in the Voxtron10 database.
The following query will show you all OLA related messages:
SELECT Message,LogEntryTime FROM [Voxtron10].[dbo].[WEB10_Log] where Message like 'OLA INFO%' order by LogEntryTime desc