Performing Health Checks on one of the environments when I noticed that one of the servers had a yellow icon next to it. Click on the VM and on the Summary tab it said Virtual machine disks consolidation is needed.

Went to the VM, right click and select edit settings > Snapshot Manager > Consolidate Disk.
The job kicked off like normal, but then the following error appeared:

The Solution:
vMotion’d the storage to another datastore to release the lock. Then vMotion’d back to the same datastore.
Then perform a disk consolidation and it will perform successfully.