When in creative mode, place 1 ender pearl in your off hand slot (screenshot 1). Next pull back your bow to full power (screenshot 2). Instead of shooting the bow, swap to an item in your hotbar which has no right click action (eg. your hand) (screenshot 3). This will fire the enderpearl but will also make the off hand slot disappear. To show it again, swap a different item into you off hand slot, this will also get back the enderpearl (screenshot 4).
MC-84043
Invisible Off Hand Slot
Resolved
Duplicate
0
The ender pearl simply disappeared from my inventory when I tried to replicate the issue in 15w31b.