This article should help engineers in solving the space inconsistency that may arise after expanding the disk.

If you encounter the issue similar to what is described below then here is the solution for the same.
Scenario: I have a SAN attached Basic Disk setup that I tried to extend from ~100 GB to ~200GB, after using DiskPart the partition appears to have expanded from ~100 GB to ~200GB, even the volume size in Disk Management shows that extra 100 GB space, but disk part and windows explorer show inconsistent disk space, it only shows ~100 GB.
Solution: The diskpart utility has an undocumented option called "extend filesystem" use this by first calling diskpart, then "select volume #" and then "extend filesystem".
1)      Open command prompt and type diskpart to open-up diskpart utility
2)      From the disk part utility execute the below commands:
a.       Execute command "select volume #" to select the volume to be extended
b.      Execute command "extend filesystem" and it should take care of the space inconsistent issue.