I tried to format a 4GB usb stick with f2fs using gparted. It formated the stick, apperently with success. But when gparted scanned that device, which it does by default everytime after completing actions, I got something like "not recognized" and the color of the partition (= the whole device) turned to black.
It's not a real problem because the stick works fine using FAT. I am simply courious.
I do run f2fs on and off on my phone
apt-get install f2fs-tools
That will install /sbin/mkfs.f2fs and activate the f2fs option for gparted
Apparently my posting was mistakable. f2fs-tools were installed. gparted formatted the stick, but didn't recognize it afterwards.
f2fs-tools seems to work for you. Maybe here it's the stick which reluctantly suffers the formatting and then refuses to cooperate.