I have a problem with free space for addions on my Pi One. After copy OpenELEC-H3.arm-7.0-devel-20161026221335-r23113-g64b34b3-opione.img.gz by Etcher on my 16GB sd card system is always freezing for a first time. After manual restart everything works ok besides free space. I see 2 partitions: 512 MB and 31MB (which is used in 95% after auto update).
It must be that first booting,automatically enlarged 31MB to (16GB-512MB=15.5GB)
if missing to enlarge,you can enlarge by gparted.
First you check you wait for enlarge much.