Howdy, so yes, I know exactly why this has happened - and its been reported before - and the issue is that I need to generate a "new" collision layer for each cultivator, (so its placement is restricted to the correct soil) as thats the only way I have been able to make it work that intended way... unfortunately, that starts to limit the total number of "plants" that can be harvested in a game.
I have the potential for a work-around - which is to remove that placement restriction - with a mod setting (but it would mean you could place cultivators on any tile, not reflective of their tree/plant) but I didn't see that as a particularly good fix.
I apologise about this issue, but its a bit out of my hands to fix as intended. Would you like me to implement the mod setting to allow it to not create any layers? i.e. is that rule-set something that you think you'll use (and not abuse ;-) )