Snap to vertices/edges/faces doesn't work anymore

Hi, I’m facing an issue with that file : test.blend (668 KB) the “snap” features doesn’t work when I move a vertex it will never snap to another, it seems like a bug to me but maybe there’s a stupid thing I did ? Please tell me.

Thanks in advance.

I think you need to enable “Snap onto itself”:

Yes, no excuse… Thank you !