I have starved within gardens of fruittrees so often now...why?

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I have researched this topic quite a lot. Some of those gardens are full with fruit and bordering fields are full with mushrooms. I have seen it myself. But others do not spawn anythin no matter how long I wait. Spent like 30 minutes today in a shag next to a garden full of apple trees and a field full of heyballs so there could have been A LOT of places to spawn in fruits or mushrooms but there where just zero. Zombies spawned in and died of old age while I waited. Are some fields bugged? It...