HW2 select multiple groups of units doesn't work

I remember when HW2 came out you could double tap A on a group of marines which selects all the marines on screen, then while holding RT, double tap on some cyclopses, and now you should have all marines and cyclopses on screen selected. This doesn’t work anymore. Now, if I want a second group I need to individually select the other units after I have all the marines selected.

So have they changed the way this system works or something or is it bugged?