I think Surrogate is indicating that if the size of the connector is ~ same as shape, then snapping might be taking precedence over splitting. Another possibility might be if there's no room for the shape where your trying to add it. Some other factors to consider:
>. Min. Shape to shape spacing
>. If new shape is allowed to move previously placed shapes
> somehow snap settings have been altered
>. perhaps some protection setting that locks behavior
>. Highly unlikely, quantum entanglement. Yep. I'm at the end of suggestions