I'm using full crystal & bowfa with simple arc light dragon defender swap.
It does not swap if i have bowfa on main equipment. Seems to somewhat work when i have melee on main and range on secondary.
When I have range on secondary it starts to spam the dragon defender when trying to swap to back to the range setup.
Edit-
I had rune pouch selected without it in my inventory, deselected that option and left defender in the bank and it seems to be working smoothly. It could have been the rune pouch setting that was causing it to freak out. I'll re-equip the defender when it banks and let you know if it was the rune pouch setting that was causing issues.
Edit 2 -
yep, I had the rune pouch option checked off without selecting the runes to go in it. Deselected that and it seems to be swapping correctly now.