Again, I have a quite strange problem: my cursor snaps to the wrong position when used with three vertices.
For testing purposes, I made an equilateral triangle:
As on the third figure, when all three vertices are selected, and I use Snap > Cursor to Selected, the cursors snaps out of center. In all other cases, snapping is correct. It snaps to the middle of two vertices, and to the center of four vertices, and Blender correctly transforms the origin to the center of mass, if told to.
Even more strange: If I reload factory settings, the snapping works as intended. So there must be some mysterious setting saved with the blend file. There are no double vertices or zero faces. I'm at a complete lost here. Please advise.