I am using Ubuntu 16.04 with an HiDPI monitor (3840x2160). Following an update earlier this week (which also broke the unity desktop) the display scaling now resets to 1 when resuming from sleep. I was hoping that this would get corrected in the upgrade from 16.04.3 to 16.04.4 but that is not the case. When the unity desktop broke I ran the following commands which eventually corrected the issue of the missing launcher and top panel:
sudo apt clean
sudo apt autoclean
sudo apt install -f
sudo apt install -f unity
sudo apt install -f ubuntu-desktop
sudo reboot
When I realized that display scaling was resetting to 1 after resuming from sleep, I tried the following commands:
cd .cache
mv compizconfig-1 compizconfig-1_old
reboot
and
sudo apt install --reinstall unity-settings-daemon
reboot
However, neither of these approaches worked. Is this issue affecting anyone else? Is there a way to prevent the display scaling from changing everytime the computer is inactive long enough to go to sleep?
Update: (7 March 2018) I can't tell if this is truly a duplicate of the issue in Ubuntu 17.04 as indicated by david6. The problem with the scaling is the same, but only when using the AMD 17.50 drivers. When using the kernel's amdgpu driver the problem does not exist. Is this the same issue? Note using the latest AMD drivers released today (17.50-552542) does not fix the issue.
Update: (26 January 2019) What an annoying problem. Since the last update, subsequent upgrades resulted in the issue being present regardless of what driver I used. After upgrading to 18.04 the issue was still there. Presently my screen now goes blank but the computer does not inter a sleep state, judging by the whir of the fans, therefore there is no more scaling reset occurring. This is fine for my desktop situation.