Not that easy to describe that for me but i do my best.
Problem is there are recipes where you shall add white sauce and when you click "lore" it asks for more mayonnaise.
I have both recipes in my cookbook, so both exist.
Actually i try to make the recipe "fish pie"(its not with optionals in the originals list so look it up here, its the one i build actually). In this recipe white sauce is mandatory and mayonnaise is optional. When i have mayonnaise but no white sauce in the pie dish, the game asks for white sauce. When i add white sauce and i click "lore" it says "Not enough mayonnaise, looks like it should use between 576 and 864 grams."
When i add mayonnaise, 1 kg, message is still the same(as mentioned its optional anyway).
When i add 600g white sauce, i get the message "You think this may well work when cooked in a cooker."
This occures with other white sauce-recipes also, in the WU-client also.