You will only see the grid on short shots, as stated above on
Flop - Pitch - Chip & Putt.
Usually you would have to click the green to see the grid and once you click off the grid disappears, with this option enabled the grid will always be there for THOSE types of shots without having to click the green.
The Space bar simply is another way of getting a reverse view - nothing to do with the grid.
:)
edit:
TheHuffer: which way is it going to roll?
One method I use to look at the lie is simply to drag the marker up and down and side to side on the green, watching for the elevation measurement.. this can be of use.