What the title says.

I have tested this by making items stackable with bigger stacks and kubejs, both do not allow items to be enchanted.

This issue will present in vanilla as well and is not something I am willing to change (due to potential introduction of side effects).

The vanilla code for Item#isEnchantable is

   public boolean isEnchantable(ItemStack pStack) {
      return this.getMaxStackSize(pStack) == 1 && this.isDamageable(pStack);
   }

which means changing the stack size will make the items non-enchantable.