1) Create a Parent 3-Row Grid, with the topmost row definition set to "Auto'. The two bottom rows can be set to 1* each.

2) Place a child Grid inside the 3-Row Grid created in Step 1, and assign it to Row 0 (the first row from the top of the screen)

3) Place a text Block inside this Child Grid element.
Normally, at this point, the first Row of the Parent Grid should resize to the height of the text block.

4) Now, attempt to create 3 rows, of 1 Star each, inside of this Child Grid.

Observe how the rows do not render as three equally-sized rows.

5) Change the Parent's Row 0 Value from Auto, to any fixed size, either in Pixels of Stars.
Observe how the Rows render properly.

Expected results:
Proportional Star Grid's rows should render even if inside of an Auto-Sized row.