How to scale with mirror modifier as if modifier was applied?

Question

From what I know the scaling action has changed since Blender 2.8 when editing while using an unapplied mirror modifier. I want my object to scale just like Image 1 (evenly towards the center from all 8 corners). Unfortunately, this only works with the full mesh and not when editing with an unapplied mirror modifier.

If I use a mirror modifier (Image 2) the mesh only scales towards 1/4th of the full geometry.

Turning on clipping doesn't help either, as then the Octagon scales into a square (Image 3).

Any suggestions?

Answer 1

1. Create a new project and remove default cube.
2. Press Numpad 7 to set Top Orthographic view
3. Press SHIFT + A, then M, then Y, to add a cylinder

4. Set Vertices to 8.

5. Press TAB to enter Edit Mode. Then Press R, and type 22.5

6. Press ALT + A to deselect all vertices

7. Drag over the entire shape to select all vertices on top, then press X, then V to delete them.
8. Press A to select remaining vertices, then I and type .2 to inset 20 cm (default radius should be 1 m)

9. Press X, then F to delete the inner face

10. Press CTRL + R, click on the top (in this view) face, then right click to create a loop cut going through the middle of it.

11. Repeat above step for the right face.

12. Press A, to select all vertices, hold CTRL, and deselect all vertices in top-right quadrant (including those on edges of the quadrant)

13. Press X, then V to remove these vertices.

14. Press TAB, to go back to Object Mode.
15. Go to Modifier tab, and add a mirror modifier. Add Y to mirrored axes.

16. Move your mouse over the viewport and press TAB to go to into edit mode again.
17. Press A to select all vertices, then change Transform Pivot Point from Median Point to 3D Cursor.

18. If you moved the 3D cursor accidentally, realign it again, by pressing CTRL + S, then W

19. Press S and scale the shape. It will keep its proportions.