Filter on report no longer works as it used to

I have a fairly complex report that I previously had been able to filter as I
wanted. For example in layout view I could click on the customer heading
then click filter in the home tab and it would give me a dropdown list of all
customers that show up with check boxes next to them, I could uncheck all
then check just the ones I wanted displayed.

We'll I've went in and changed some formulas and controls (nothing changed
with customer name) and now every time I click filter in the home tab it just
gives me the right mouse menu over the customer heading, for example equals,
does not equal, begins with etc.... nowhere can i get my list of customers
and check them off. Any idea what I changed to make this happen or how I can
get my better filter options back?