After the excitement of discovering Mike's latest enhancement to the forum I downloaded one of the kits you posted (Acoustic) and loaded it into a Beatbox (Windows version). I tried assigning open and closed hi-hats to a mute group by checking the boxes in Group 1 but it made no difference to the way the open hats played. They weren't cut off by the closed hats no matter how quickly I played one after the other. I was playing them on the keyboard rather than sequencing them.
Any ideas why that doesn't seem to be working properly?