Pure Capsaicin
https://support.microsoft.com/en-us/kb/3059372
If that still does not help try the below:
Do you have multiple avhdx or avhd files on the VMs? Do you see those? If so you will need to merge them through the Hyperv Console.
https://trevorsullivan.net/2016/07/24/merge-hyper-v-disks/
Please make sure to make backups of your system prior to doing anything. You should also think about doing a System Cleanup for unnecessary files and updates on the servers (If there is no space internal to the VM).
See how to merge Hyperv checkpoints:
http://www.altaro.com/hyper-v/how-to-merge-hyper-v-checkpoints/