When the dropdown (RequestedByDropDown) is blank I get no results (as designed). What I want is to return all values, and then just those that match the values in RequestedByDropDown. For this I think I should be using the search function. I have therefore tried:
I haven't tested this but my first guess is you need to change your line to add DisplayName so Requested_x0020_By.DisplayName since that is what you used in the Filter. Sorry, about to jump on a call so I cannot recreate it all but that is where I would start. Create a new screen and get rid of all of the complexity and try to make it just work with simple text against Requested By. Then plug that into mega function.