Just read your edit, I'm the one who volunteered to bug hunt in the first place, it's not a problem, no need to feel bad
Thank you for that. It seems I actually figured out how to solve the bug but I need some more testing cuz it's not quite amusing to repost. Anyway, the problems seemed to be that when a zombie ate a plant, it didn't just reset the state of that tile, instead it reset the state of EVERY SINGLE TILE. That's why it kept being like that. However, now I added a condition that if a plant is above a tile, it automatically sets its state as an ocupied tile. This should work now.
Edit: Still trying, I'll let you know when it's done.