HELP SSRS COLLAPSE/EXPAND refreshes only on default param values

SSAS and SSRS
1

I have a report with 8 filters all filters have a defaulted value,
I then created a new hidden parameter to Expand and collapse my columns that are toggled.

The problem is that if i choose values other than the defaulted param values and click on expand or collapse it defaults back to original defaulted param values thus only collapsing/expanding default values not the new values in the drop downs.
the expression behind my radio buttons is IIF(param!someparam.value = 1, "Radio_On","Radio_Off") and IIF(param!someparam.value = 0 , "Radio_On","Radio_Off")

My default value is 0 (Collapse)

2

I have seen some cool things done related to maintaining a "state" in SSRS with global variables. This may not work exactly the way you want but I think it gives you an idea of how to move towards your goal. It's an option to consider.

SSRS Global Variable and Code