If you haven't already, try also adding the Cost metric (from Calculations perspective) to the Values section of the ad hoc query configuration dialog.
If the cost pool column is still blank, then something may be a bit off in the Cost model between the two relevant objects (Cost Source and IT Resource Towers). The model itself is a good place to investigate further.
In the Cost model, right-click the IT Resource Towers object and Trace (i.e. trace all of its rows at once).
Hopefully the Cost Source object is one of the ones lit up (in bold) during the trace, implying IT Resource Towers can trace at least one of its rows back to the Cost Source object.
With the trace still active, select the Cost Source object.
It may take a few moments for the Summary Data table to appear at the bottom of the screen, since you're drilling from one object to another.
Right-click any column name in the Summary Data table, then: Show/Hide columns > Cost Pool (and Cost Sub Pool).
Hopefully the Cost Pool column has valid values, not just blank cells.
By conducting this model trace, you're replicating what the report table is doing.
If the model trace works as expected, then something may be amiss with the report table instead.