The default number of points (if you don't specify a number) is 3. You should be able to say: G29 n 2 to get 4 points (2x2) probed. Please be aware that it would be: G29 P 2 in the GitHub code. You should probably leave the
Code:
#define AUTO_BED_LEVELING_GRID_POINTS 5
Just because you have space declared for a bigger set of points doesn't mean you have to use them.

I do suggest you load up the RCBugFix when you have time. It has a lot of good stuff in it. And you will need to have your settings crossed over to it's Configuration.h format to run the Unified Bed Leveling that is coming out soon.