When I open gparted, I got below:
sudo gparted ====================== libparted : 2.2 ====================== Device /dev/sdc has a logical sector size of 4096. Not all parts of GNU Parted support this at the moment, and the working code is HIGHLY EXPERIMENTAL. Ignoring device /dev/sdc with logical sector size of 4096 bytes because gparted only supports a size of 512 bytes.
/dev/sdc is the external hard drive (WD Elements 3TB).
It seems gparted doesn't work with this hard drive. Any clue?