Most of the tasks in the Reaper's Rewards event are not being marked as completed in my game. I have planted so many tulips and snapdragons, in planter boxes, on the ground under cover and not and the tasks are not being marked completed. Also, I do not know if this is how the event is supposed to work, but the entire list of tasks resets every time I launch my game. If I complete some of the tasks (buy seed packets, ask about Ambrosia, etc.) they get marked completed, but if I save, exit, then relaunch, I get have to do those tasks again.
That has a thread here: Reaper's Rewards: Planting Flowers/Trees not checking off | EA Forums - 4972107 although for most it's related to Better Build Mode.
To be sure, you repaired your game as well ?
You might need to plant something again after doing the steps. Maybe even change household/save and try it there.
