Screen "un-blanks" after "blank" is initiated

[pfountotos]

Hello folks, long time Debian user here. I have encountered an issue regarding "screen blanking" using the default XFCE Power Manager. This issue arose immediately after Changing my LED monitor cable from an analog VGA cable to a digital DisplayPort cable. Once 5 minutes has elapsed, precisely as set in the Power Manager settings, the screen blanks, my monitor reports it's going to sleep and then does, and then immediately POOF the contents of my screen have reappeared! The cycle repeats on and on. I tried re-installing the Power Manager thinking there is some sort of "reset" required to account for a digital interface (vs. analog) from the monitor to the PC but that didn't work. Any thoughts are appreciated!

EDIT: I tried Debian XFCE Live (Stretch) and verified the monitor blanks properly and stays that way with a fresh (or live in this case) instance of Debian XFCE. The system with the issue is the latest stable version of Stretch as well. I honestly have no idea where to look for this type of configuration issue but based on the verification above, there's probably one flag somewhere that needs to be changed. Any help would be appreciated.

EDIT: I tried resetting display and power manager settings to the default settings I found in the XFCE Live system, under the Settings Editor. There was a VGA entry in there that I completely removed but it still doesn't work right. I'd hate to reinstall the system for something this small but using the screen locker or physically turning off the monitor are a pain.

[debiman]

so what are xfce4-power-manager's settings?
also, output of

Code: Select all

systemd-inhibit

please.

[pfountotos]

so what are xfce4-power-manager's settings?
also, output of

Code: Select all

systemd-inhibit

please.

Hello debiman, thank you for your help! Please find attached per your request:

Output of systemd-inhibit:

Code: Select all

Who: NetworkManager (UID 0/root, PID 494/NetworkManager)
What: sleep
Why: NetworkManager needs to turn off networks
Mode: delay

Who: ModemManager (UID 0/root, PID 474/ModemManager)
What: sleep
Why: ModemManager needs to reset devices
Mode: delay

Who: xfce4-power-manager (UID 1000/tuddy, PID 1136/xfce4-power-man)
What: handle-power-key:handle-suspend-key:handle-hibernate-key:handle-lid-switch
Why: xfce4-power-manager handles these events
Mode: block

3 inhibitors listed.

The forum is not letting me attach a screen-grab of my power settings. It says the forum quota has been reached.

EDIT: I did a small screen-cast for the power settings. I have tried all combinations in this area and the same issue occurs, screeen blanks and then comes back on immediately.

https://youtu.be/ZSF4StlvCvM

[pfountotos]

EDIT (10-11-2017)
After doing some research, I tried the below code and made a script of it in case it worked so I could manually blank the screen. Same issue occurs! Once the screen turns off, several seconds go by and it comes back on!

Code: Select all

sleep 1; xset dpms force off

I also issued 'xflock4' via a keyboard shortcut and that keeps the screen turned off.

I hope someone might have an answer or somewhere to check a setting. I appreciate any help/advice you might have.

[debiman]

Same issue occurs!

my bets are on an ACPI problem.
something about your hardware requires you to add something to your kernel commandline (edit /etc/default/grub, update-grub).
what? search, try, search more, try again...