OK I got it now, I was a bit confused on which users you were refering to where.
I personally have never used roles. I have always either used a employee's department or some other data as the condition but as far as I know they work. If you have one user you could check for them explicitly although I believe you are having some issues getting their user name from your other post.
I will assume you are using the lookup to specify the user and it includes the domain name. I believe it also needs to be the initiator.
I just created a blank form, created a "test" role that was Yes for Default and Yes for Initiator and put my account in as a member. I set a conditional format for User role is equal to "test" shade the field orange. Preview - > the field was orange. I went back to design and switched it to user role not equal shade orange. Preview -> not orange.
I would check the initiator and do some simple tests. I am not sure if there is a way to display the users role, I am guessing their probably is, but either the role is not getting turned on when the form is opened or it is not set up right.
I would do some basic testing and work your way back into it.