I've encountered this problem several times. When Gparted, Diskpart, Disk Manager fails me (often times before) I use BootIce. I'm sure there are other alternatives but this is one of my many recommendations and I've found to be more convenient and portable than EaseUs, etc... mention in the link.
It's never been my "go to" program but it does offer more functions, control and user friendly interface than DiskPart and Disk Management. ie: more say over partitioning, specifically the "hidden" partition mentioned in the link, drive letters, etc... check it out, if it doesn't work, let me know.