When loading an older save, conveyor loader selects a whole category instead of one item.
Originally, conveyor loaders in hatch stables were to select meat. On load, there is only meat and pacu fillet in the category
Unpausing reveals more items and all are selected
On another save, that lead to every food ending up inaccessible (on load - unpause pictures)
Also, some ingredients and elements need to be rediscovered in order to be selectable again (e.g. meal lice for the above conveyor loader)
Load an old save and check if conveyor loader still has the correct elements selected