According to https://specifications.freedesktop.org/desktop-entry-spec/latest/ar01s05.html, the OnlyShowIn key is matched against the value of the XDG_CURRENT_DESKTOP environment variable. So we can trick unity-control-center into showing all the panels by running
env XDG_CURRENT_DESKTOP=Unity unity-control-center
This seems to work fine.
Under Ubuntu 17....
For anyone reading this and having a similar problem, I just managed to fix this, by simply purging the unity-control-center. This will change the default one to the gnome-control-center.
Since the reasons I still use unity weren't really connected to the control center this was imo the most future-proof solution.
So a simple
sudo apt purge unity-control-...
I am experiencing the exact same issue.
If you don't need to use networkd i think your issue can be solved by adding this file /etc/netplan/01-network-manager-all.yaml with these contents to your netplan directory.
After you have added this file make sure there aren't any other files in that directory ...
I managed to resolve it myself by doing a workaround via alacarte for each problematic applications;
Open up alacarte and navigate to your application (you can manually edit, but make sure to know what to do. Using alacarte is the safe way)
Add this string before the actual command: env XDG_CURRENT_DESKTOP=Unity
Save, and close
(Optional) Manually modify ~/....
With the unity-control-center command line if you press Tab Tab after typing it in it will show you all the options you can bring up.
appearance info power universal-access
bluetooth keyboard printers user-accounts
color mouse region --...
Two options here:
You should try to fix this with debsums. You can find missed files with it and reinstall their packages with the following commands:
sudo apt-get install debsums
sudo debsums --changed --silent
then reinstall mentioned packages manually with
sudo apt-get -f install
Or try to find all packages, which have files in /...
I recommend you to restore Ubuntu from live CD. Download the iso and reinstall Ubuntu. It is the fastest and best way to fix your problem. Othrewise you can run sudo apt install --reinstall ubuntu-desktop and sudo apt install unity. After these commands you might need to run unity on a terminal
Of course I figure it out less than 24hrs after posting.
I found that lsusb was hanging. I had a DELL S2340T monitor plugged into one of the USB3 ports (the monitor is a hub and also supports touch via USB...DisplayLink, etc.). Unplugging that fixed lsusb, allowed unity-control-center to display, and also fixed a hang-at-logout problem.
No idea whether ...
This was a bug that has since been patched. The version of unity-control-center shown in your output from apt-cache policy unity-control-center is out of date.
I issued the following commands:
sudo apt-get purge unity-control-center
sudo apt-get install unity-control-center
sudo apt-get install unity-control-center-signon
Note the change in output.