I have the same bug, or at least a variant of it. No mods.
When I try adding a full cabbage to a roast, it works fine.
When I try adding a partial cabbage to a roast, it doesn't work.
When I try adding a food item with less than 10 hunger points in it, it doesn't work.
On another note, I feel like I am the one player of our MP server who constantly generates backpacks / ovens that generate items. I think 95% of my pancake ovens have become permanent pancake generators, and 95% of my dropped backpacks have become sources of pop, pipe bombs, and newspapers.