WebI issue with hierarchy display and aggregation

Question

Trying to wrangle what looks like a defect in WebI's handling of hierarchy display and aggregation. We just completed an update cycle and are running BOBJ 4.1 SP4.
The hierarchy is a standard FM Commitment Item hierarchy in which both the nodes and leaves are Commitment Items (i.e. it uses InfoObject nodes, not text nodes). An example of one of these nodes looks like this in BW:
Cmmt_Item A - Node
    Cmmt_Item B - Leaf
    Cmmt_Item C - Leaf
Let's pretend Commitment Item A has $50 posted to it, B has $20 and C has $30. Analysis for OLAP handles this by adding a virtual leaf line to distinguish postings that are on the parent node like so:
Cmmt_Item A - Node       $100
    Cmmt_Item A - Leaf    $50
    Cmmt_Item B - Leaf    $20
    Cmmt_Item C - Leaf    $30
So you see both the total for the node ($100) and a line for each Commitment Items with KFs posted to them. Our users like this. They can easily see the aggregation and the breakdown.
WebI, on the other hand, will display it like this:
Cmmt_Item A - Node       $150
    Cmmt_Item B - Leaf    $20
    Cmmt_Item C - Leaf    $30
It doesn't create a separate line for the value of the parent node, but it does add it's value into the aggregate. Twice. Modifying the table with the 'avoid duplicate row aggregation' checkbox yields output like this:
Cmmt_Item A - Node       $100
Cmmt_Item A - Node        $50
    Cmmt_Item B - Leaf    $20
    Cmmt_Item C - Leaf    $30
We're about halfway there. While the top row now shows the correct aggregation and it creates a new line to show the distinct amount on the parent node, that new line appears on the same level as the parent. It's no longer clear that there's an aggregate and a breakdown. And attempting to expand or contract a node will now crash the report with one of those 'Error 16' messages.
Has anyone encountered this issue with hierarchies in WebI? This report was built from scratch in 4.1, so I'm not sure if this affects older versions or not. Or if it would affect any hierarchy that uses InfoObject nodes instead of text nodes.

Answer 1

Without a fix, the simplest workaround I can think of would be to restructure the hierarchy. It can't use postable nodes, so Cmmt_Item A  - Node from my example would need to be converted into a text node and the postable characteristic added as a child on the same level as the B and C leaves.
This looks like it would affect anyone using hierarchies with postable nodes in a WebI report.
Another oddity in WebI's behavior here - even though the postable nodes show incorrect sums the sum at the root node is correct. So extending my examples from the original post:
Root Node                    $100
    Cmmt_Item A - Node       $150
        Cmmt_Item B - Leaf    $20
        Cmmt_Item C - Leaf    $30