Unfortunately there's a step missing in the instructions you followed so I will amend this now. Apologies for this. You have to create a new template under the object designer and then you also need to modify the attribute on your window to say which template to use. So for example for the Impact drop down:
I didn't need an IIS reset but then I have all components installed on one box
Does this work any better?
Rather odd behaviour I'm seeing.
We have the Company/Customer/Raise User filters applied.
Clicking on the raise user to view the list gives a normal drop down list. As does typing in the box.
However if you select the Company/Customer first then the complex list is displayed correctly.
Note in the first example that the filtering is actually working - typing "ron" is showing the user "Roy Abel" because one of the template attributes has "ron" in the string.
It looks as if there was a similar sounding problem raised with 7.3 which was due to having customised filters on the raise user (problem 4334). This was fixed in 7.3.1 though. I'm not certain what version you are on but if it's 7.3.1 or later then I think you may need to raise a support case so we can investigate your design.