My passport can't be partitioned

I am trying to format a WD my passport in exfat on a MAC High Sierra 10.13.4.
After erasing in exfat with GUID partition map, I want to partition it but on the partition
window it says that there 103,5MB of space utilised and this volume can’t be partitioned.
Any help with this? thanks.

Hi Dado,

You should follow the steps provided in below article to reformat the My Passport in macOS Extended File Format to use on Mac. It is recommended to backup the important data files from My Passport before going to reformat the drive.