I'm sorry to hear, you're facing these troubles. I’ve just done some tests of the Edge Boundary Checking
mode in Layered Lawns
presets and it works just fine here on the mentioned configuration. As it's really hard to say, what's happening in your scene just from the provided screenshot, if possible, please feel free to send us
your scene (ideally simplified and containing just this problematic object(s)) to check it here. Thanks in advance.