Why is Dirk's lil cal empty? Shouldn't all lil cals be filled with arquius, half of gamzee, and caliborn to make a stable timeloop? Or did lil cal just suddenly went empty when it went through the post scratch portal, but not the pre scratch

It was when it split for the Scratch. Pre-scratch Cal had the souls in it, but 2 of the same jujus can’t exist at the same time so Dirk’s lil Cal was emptied out.