Webi Bypassing BEx Authorization Variable with SAP Exit

BEx query has Hierarchy Node Variable with Authorization as processing type. Its set as User Input ready

When the Webi report is refreshed, the LoVs appear as per the Authorization. However, if user doesn't select any value (pushes from right to left in variable screen) he gets NOT_AUTHORIZED error. Which is not intended, it should check the authorization in the background via SAP exit and populate the result. This is how it runs inBEx query.

However, in Webi it's giving NOT_AUTHORIZED error? This is how the product is designed to work or is it a bug.

I see several forum threads and SAP KBAs/notes but they are not answering my question. Could anyone please help.

I am ready to provide more details on this error.

Thanks,

Tilak