Hello, if this may help, I've fixed the issue in a different way.
The symptoms: extended vmdk using vsphere client from 50 to 60 GB. Extended windows volume with disk manager in server manager. Invalid parameter error. Disk manager and diskpart then showed a 60 GB drive, partition and volume while Explorer still got stuck to 50.
The solution: extended vmdk adding 1 more GB (from 60 to 61). Extended windows volume using diskpart. Then disk manager, diskpart and explorer correctly showed a 61 GB drive. Issue fixed.