Running the "Reclaim Disk Space" action on all my Windows VMs (Windows 10, 8.1, 7, Vista, XP) corrupted their disks. When trying to launch the VMs some of them start with "Preparing Automatic Repair" and other just present a black screen. Trying to repair the disks was not successful. I had to restore the VMs from backups.
Using the "Reclaim Disk Space" action on macOS or linux VMs seems to work fine.
I'm using Parallels Desktop 12 Version for Mac Pro Edition (Version 12.1.2 (41525)) on a MacBook Pro (late 2016) running macOS Sierra 10.12.2 (16C67).
All disks use the "Split the disk image into 2 GB files" option and have the "Real time virtual disk optimization" turned on.
This looks like a fatal bug to me as it results in data loss.
Last edited: Jan 19, 2017