Is there a reason why you are using 9.3.1? 9.3.2 is the latest version, might be worth to try and see if that fixes it.
https://support.citrix.com/article/CTX235403/updates-to-xenserver-vm-tools-for-windows-for-xenserver-and-citrix-hypervisor
The problem was that this coworker moved some settings to a different GPO, so a whole bunch of settings got put back to not configured and behaved differently.
I looked up the initial change and this was about turning the display off after x second when connected to a the net or a battery. (so i guess the affected setting was in the same area)
We had this issue some time ago, turns out someone had messed with the power setting gpo and removed something what they shouldn't have.
We had the exact same symptoms, have you looked in this direction?