Coherence mode not working with PD10 on iMac 5k with Windows 8.1 for multi users

After setting up PD10 on iMac 5K with multi users, we noticed that only the first user launching the VM in coherence mode will have it working properly. Subsequent users would end up having their windows end up as phantoms (not showing) - symptom is when you show the windows under mission control the windows are just blue without actual content and they don't show up on the main desktop.
Each user has their own VM although the were all cloned from the same VM - reason for the separate VMs is that we were getting permission issue when sharing a single VM despite trying all the options of setting the permissions based on the few threads we could find.
Anyone got any clues as to how this can be corrected?
Thanks