This is definitely a bug because as you mentioned we are able to plant things in the ones in Moonwood Mill, but not in Henford or Evergreen Harbor. I wasn't able to test this, but I wonder if this issue is present in City Living because I know planters spawn at some of the festivals.
Actually, I don't think it is a bug. Active Sims have never been able to plant in off-lot planters. The planter boxes in Moonwood Mill are the only exception I'm aware of and that's a different planter box, Kristopher's Planter, that is unique to the Werewolf Pack. It appears that either the world of Moonwood Mill or the planter box has added the ability to plant off-lot, but that doesn't mean the ability has to apply anywhere else.
@Sketch793 What's the point of them even existing in the world if you (the player) or townies can't plant anything in them? It seems pointless to have planters in the world if you can't even use them.
I agree that it seems pointless to have empty planter boxes. However, I didn't design any of the worlds, so I have no idea why the developers put them there.
