Using the latest version of DE. Was wondering if I was possibily doing something wrong, because I can no longer do this from the gui like we used to be able to.

It’s no longer done in the gui. Instead you enchant it how you normally do

That doesn't take away from the fact that I still can't put anything other than infinity on it. No power or anything like that

Just tested this in dev and everything works fine... Is it possible something in your pack is messing with bow enchants?

Most methods of enchanting don’t let you enchant items that already have enchantments. Maybe that is your issue?

I can enchant the bow via anvil, but the power enchantment doesn't seem to do anything. Using a not upgraded wyvern bow with maxed damage and speed I deal 12 damage to skeletons/zombies. After applying power V the damage is still 12 (they survive the first shot with 4 hearts). This might have something to do with your enchantment toggle handler, since there is no toggle option inside the bow gui.