Can you try wrapping a different way, Danni? Natalie is pretty good at getting her arms out however she is wrapped, but the most effective way for us is (lets see if I can explain it, LOL):
Fold one side of wrap over arm but under body
Fold other side of wrap over other arm but under body
Fold bottom of wrap up to shoulders and tuck around the outside
I hope that makes sense - its the best I could do! Hopefully you and Mason can work something out.