Furnaces, blast furnaces and smokers don't cook without fuel in the bottom slot, even if they are already fired up

I was playing on my hardcore world that I just updated into the new snapshot and I noticed that the furnace wouldn't cook items and I was confused until I put a piece of coal into the bottom of the furnace and then I realized that the only way for the furnace to cook was to have an extra piece of coal in the furnace at all times. I wasn't able to test this with different items but I did include a video to show what is going on.

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