I was working with the Snap to Grid option and due to the unexpected result obtained I would like to show you the case that can be summarized as follows:
- I take a Cube (2x2x2).
- Set the Z dimension in 0.
- I set the Cube in Edit Mode and selected a vertex that was move to the right side.
- I made “Snap to Grid” and the result was the vertex goes to the Object Origin and not to the nearest grid intersection.
In the following link there is a PDF with pictures that illustrate the case:
https://drive.google.com/open?id=0B1emiHzIWh8eMzZNTFBHWHc5Y0U
Cordially, Ricardo Amaya R.