Minecraft Username: @LJKAzrael Brief Description: When a tool is "saved from the brink of destruction," it poofs from existence. Instructions: 1. Fish mobs. 2. Wait for your tool to be "saved from the brink of destruction" 1% durability (it functions properly when the tool is automatically repaired 10% durability). The tool will be repaired, but it will also appear in a new place in your inventory (it won't move to the offhand but will move from it as well). I have not had it remain in place even once after being "saved from the brink of destruction." If your inventory is full, the tool (while most likely repaired) disappears from your inventory. How many times did you recreate this bug?: Three times. I only tested it with non-enchanted fishing rods. Result: The fishing rod disappears from your inventory. Expected Result: The fishing rod remains in your inventory, if not in the same slot as well. Evidence: Takes about 3 minutes to recreate.
Duplicate and/or new side effect of https://www.ecocitycraft.com/forum/threads/bug-report-fishing-rod-auto-repair.161006. According to Jamie this is intentional. I tested that specific case when the fix was released, it worked fine for me. I will probably test it again later today.
It moves about randomly in my inventory, sometimes in the hotbar sometimes not. If there is no open spot for it to jump to, it just poofs away. EDIT: If there is open room in the hotbar, it will just jump around the hotbar randomly. If the hotbar is full, it will place it somewhere in your inventory. And if that is full as well, it just disappears.
Item is removed from inventory (from it breaking) and then is added back. Due to how the priority systems work, there's a bit of a lag(1-2 ticks) and the item is added before it's removed, so the slot isn't actually available to use. Changing it (the priority) could fix this, but dangerously also adds the possibility of not catching all item breaks.