Hello,
The behavior is likely associated with a permission issue with one of Parallels Tools configuration files (which is located outside of the application bundle, and thus does not get deleted when you delete the app).
To try to resolve the issue, please, perform the following steps:
0. Make sure that your Desktop items are visible.
1. Open Terminal (Applications > Utilities > Terminal) and execute the following command:
Code:
sudo rm ~/Library/Group\ Containers/4C6364ACXT.com.parallels.toolbox/Library/Preferences/4C6364ACXT.com.parallels.toolbox.plist
(You will need to enter your Mac password to run the command. No symbols will be shown due to security measures, so just hit the keys and use Return/Enter.)
2. Restart Parallels Toolbox. Try restarting the Mac and check if "Hide Desktop Files" is triggered again. If yes, please let us know, and we will create a support ticket to further investigate the behavior.
And in any case, please let us know about the results.
Thanks!