It seems that if you harvest enough food, it will provide 1 population instantly, but the number of food left in the stack will not be as intended afterwards. For example, if you harvest 90 food for a 1-pop city, it will grow to 2 instantly, but sometimes still take more than 1 turn to grow to 3. Sometimes it even not grows to 3 but start telling "lost at X turns". But growing from 1 to 4 cost only 72 food in total so I expect it to grow to 3 in 1 turn and 4 in the next turn, with at least 18 food left in stack. Anyone experienced this before and figured out how this works?