how to loop within a loop

I have the latest software with Mixon4, while looping a beat, I switch to loop roll, while beat is still looping 8 beat for instance, I hit the the pad for quarter loop roll on fourth snare, the program automatically does a quarter roll at the beginning of the 8 beat loop.
why can’t I do a quarter loop roll or any loop roll within the 8 bar loop without it going to the beginning of 8 bar loop