Are you doing a rest period after the mixing is complete, before the kneading Action takes place ?
Chau also does a couple of folds as well and then puts it back to the machine to further knead.
I do not have these mad craft skills not the instruments, so i am thinking about how to enlage the center post, which also should decrease the gap to the inner blade.
However, there is still dough curling up at hydrations beyond 62% (between the blade shaped arm and center shaft). Also, the blade does not reach down enough to push the dough back to the arms in the center of the bowl. This your extension does