... I tried 8mm AP on it with similar results but to be fair it's still a new cord and maybe needs some break in time? With 7 wraps it wants to break down to 6 wraps 1 braid...
The hitch cord will change as it breaks in but that is probably not going to make a big difference. Have you tried using less wraps with real short tails? Also try some fat rope if you can get your hands on some as that can make a big difference.