I am not sure if this is what you mean, but there is no Vertex in the cneter to Snap to.
You should be Snapping to this Vertex (or the one on the opposite side):
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Omar Domenech
replied
Also sometimes if snapping is misbehaving, I like to change it to "active" and just set a vertex as the active one by selecting it and the thing will always snap to that one without issue. It's a good way to specifically snap exactly to where I want.
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