Bundle Item Deletion Upon placement in chest connected to furnace hopper

With my first incident, a bundle (almost full of iron blocks, gunpowder and bones) was placed in a smelt material input chest above a hopper (connected to a furnace) that was already full of smelting materials. The bundle itself did not move, but appeared to be emptied instantly. All items within disappeared, seemingly deleted. I tried again with the same bundle, filled partially with torches, they vanished.

I experimented a little with full and empty hoppers, smelt/fuel placements, and whether the furnace being active effected the bug. The result was the same:

Bundles placed into a chest which is connected to a furnace has all of their contained items deleted. The bug appears to be specific to the furnace, does not occur with chests connected to chests. The bug occurs when the bundle is placed adjacent to both smelting and fuel hoppers. It occurs instantly, not when the bundle itself moves through the hopper. It seems all items are effected the same, it didn’t matter if they were compatible as smelting material or fuel, when they were, they didn't end up being used.