As seen by the two screenshots, the electric grills have accumulated a large amount of food. This food never gets cooked. One way to resolve this issue is to empty the storage. The duplicant will then reload the grills and a normal buffer is re-established. This only happens after a number of cycles, and I wanted to capture this before I destroy them and move the grills.
The first grill has only ever cooked barbecue and pepper bread; the second grill has only ever mushroom and gristle berry (gristle berry hasn't been cooked in a long long time, hence bristle berry does not show up in the buffer).
If I had to venture a guess, the grill never fully matches portions of ingredients together, causing these remainders to accumulate.
Steps to Reproduce
Build a grill and let it run for 100's of cycles; save file is attached.
This issue has not been confirmed by a developer yet.