A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
Not trying to justify the action just trying to explain what I think is going on.When you click the slide to insert a shape / textbox PowerPoint tries to insert a 1" square shape. It it's a textbox then it shrinks to a minimal size.
The effect of this is a center aligned box will think the cursor should be 0.5" right of where you click (and probably lower) and a right aligned box 1" right of where you click.