I decided to create this post simply as information for people who might have this problem.
I needed to install Citrix Workspace (ICA Client) to remotely access a workstation. Specifically, version icaclient_26.01.0.150_amd64, but after completing the installation and restarting the computer, all zorin-os-* extensions were disabled and impossible to re-enable. After some testing, I discovered that the problem is caused by the AppProtection service, which is optionally installed along with Citrix Workspace.
The fix to get things working correctly again was to uninstall the ICA Client and reinstall it without AppProtection and DeviceTrust.