Yes, this is a known issue or limitiation (or may be it's designed that way). At the point where you are looking, IDT always passes on a select * query to the analytic view (olap cube) and that won't work.
You need to explicity distingush the attributes & measures in your analytic view within the IDT as described in SAP Note 1609126 after which the IDT knows which fields are measures and subsequently be able to automatically add SUM() and Group By clauses to the SELECT statement that it generates. However this is only possible after you create your data foundation within the IDT.
So, a 'Show Values' before that will always give you that error message.
Thanks,
Anooj