This may be a general extensions issue, but it occurred when I tried to install PlatformIO.
Clicking “install” switches the state to “installed” and flips the button to “uninstall”, however no installation scripts run (like attempting to install the PlatformIO CLI, etc.) no restart notification.
I have not seen any errors when viewing the debug console, however I do see an empty “Extension Host” object.

Is there some global configuration or permission, or worker thread preventing the extension install from kicking off?