Hey!
Please make sure the quad texture is being imported as a texture, not a sprite. Not sure if that would be the exact cause, but that's a start. You've already tried resizing the sprites on your texture to give some space between quads, but can you try shrinking the texture even more? Quads are essentially just manual UV maps, so I think the first quad is reading info from the second and so on.
That said, there might be an issue with insanely big sprite sheets for Quads that I haven't solved yet, so this might be related to that? Hopefully shrinking the texture even more solves it, but I'm hoping it's just a certain import setting somewhere on the texture.