Hi Felix, yup the ellipse corners command (the third one in the ellipse command set) only picks 2 points and makes an axis aligned ellipse.
But the ellipse from center point has 3 picks in it, not 2 picks like the rectangle center command has.
So basically since it has 3 picks in it it behaves similar to the rectangle 3 points command.
If you use either the ellipse from center point, or the rectangle by 3 points command you should see that they both use 3 picks and they both behave similarly where the first pick makes some base point, the second pick makes an x axis direction, and the third pick makes a y axis direction.
So 3 picks for ellipse behaves the same as 3 picks for rectangle, I guess I don't see how that's odd...
The button icons show a little circle point there for how many picks each command are going to take, notice how the ellipse center command has 3 dots in it? That means it uses 3 picks.
If the ellipse command did not use 3 picks then you would instead be picking a kind of corner frame for the ellipse, and that's somewhat slightly odd for an ellipse since there is no portion of the curve that actually goes through the corner. That's why the first 2 ellipse commands are more focused on picking a major and minor axis point since those are actually points that the ellipse goes through.
 Michael
