Meshdrawer2D's space

Meshdrawer2D, used in an off-screen buffer, seems to have odd boundaries.
In the same element mentioned above, I’m using Meshdrawer2D to draw a number of rectangles to an off-screen buffer. When doing so using quads loaded from an egg file, if I recall correctly, this worked as expected. With MeshDrawer2D, however, my rectangles seem to be clipped oddly.

To be specific, with the MeshDrawer NodePath simply parented to my offscreen base NodePath and no position or scale specified, placing a rectangle at 0, 0, offset to be placed by its centre, seems to result in its left- and bottom- sections being clipped, as shown:
(The red-orange section should extend further to the left and bottom, I believe)

Offsetting both the MeshDrawer2D NodePath and my rectangle positions seems to allow me to place them as desired, but produces more awkward positioning.