Active furnaces delete their contents when unloaded

Smelting items in a furnace, then unloading the chunk it's in causes the furnace to lose their contents when the chunk is reloaded, but still showing the lit texture (if it was still supposed to be smelting)

What I expected to happen was...:
The contents of the furnace remain intact

What actually happened was...:
The input, output, and fuel slots were empty

Steps to Reproduce:
1. Begin smelting anything in a furnace
2. Walk/fly away
3. Return to the furnace. The contents should be gone

As far as I can tell. The contents do not get deleted if the furnace wasn't smelting anything when it gets unloaded. It only appears to be when smelting