@roman126 same problem for me. A recalbox v4 16gb in a 32gb sd card and it still see only 16gb of free space. i've tryied everything but i've found no solution.
i've noticed that in RETROPIE sometimes there's an option called EXTEND SD but in my image i've only recalbox....how can i install in it retropie??
This answer is more a question... 
