Crosstab sort on nested nodes

[navissar]

Hi everyone,
This is a very weird thing - Cognos quirkiness at its finest. I have an environment that I upgraded from Cognos 10.1.1 to 10.2.1 FP2.
All is absolutely fine except for two reports. These reports are relational over CQM. Each has a Crosstab which has some measures on columns, and then three data items nested in rows: say for example Agent Name as the outer-most node, Customer Code as the middle node and Customer Name as the inner-most node.
Now, for each salesperson the customers are supposed to be sorted by one of the measures. Problem is, we can't apply sort on the inner-most node because the middle node is numeric and it groups by the middle node, so the crosstab will end up being sorted by the middle (Customer Code) node.  If I apply the sort to the Customer Code node, the report runs forever and eventually times out. 
Now, there are many ways around it (I could concatenate the code and name together in one inner-most node, for example), but what drives me and my customer crazy is that this report worked perfectly on 10.1 (With sorting on the Customer Code node).
Anyone seen/encountered/has a clue why Cognos is being mean to me?