Finally resolved this by selecting Action > Rescan Disks in Disk Manager and then I was able to extend the volume normally.
"Not enough space available..." error when trying to extend simple volumes on a Dynamic disk on a virtual Windows server
I have a virtual Windows 2012 R2 server hosted in a vCenter cluster and after adding 50GB of space to the disk I logged into the VM and pulled up Disk Manager to extend the volume, only to find that it is a Dynamic disk with multiple E: partitions (see screenshot).
When I try to right-click and choose Extend Volume on any of the volumes in the disk I receive the error "Not enough space available on disk" (see screenshot). I have tried lowering the amount of space to extend it by but I get the same error.
I've read several articles regarding the error and also regarding dynamic disks, but none seem to focus on this specific scenario. It's almost like Windows doesn't think the Unallocated space is next to the partitions, even though there's (seemingly) no other volumes in the way.
-Aaron