I’ve had this happen when I’ve had multiple copies of sprites on top of each other. Did you generate the ground by copying and pasting a row of dirt? I’d suggest highlighting the row in the editor and deleting (and possibly replacing).
If the Grass & dirt sprites are not placed separately, then are they part of a panel sprite? If they’re not the latter, maybe making them a panel sprite may otherwise solve it?
It has happened to me. Does it appear in the editor when you zoom in and out? What I did was just overlapped the two objects a bit so that the objects don’t make a gap when the scaled