I got a notification on my Win 11 box that there was an update for the Hub and I  starte the update process. After some time,  double-clicking on the Reallusion Hub shortcut didn't seem to do anything (ie the app would not open) I coulde see the hub icon in my taskbar, but interactoing with it did nothing (no options but to activate the app, which did not work).
I did a cold boot of my machine and the problem persisted, the icon shows up  in my taskk bar, but the app never opened.
I was just about to start writing this when I decided to try using the task manager to force the hub to quit. That did the trick! After I forced the app to stop, I could double-click on the shortcut on my desktop to launch the app as per usual.  I just used the new verion of the app to update my iClone8 and CC4 apps to their current versions as of today.
Obviously, no action is  required on anyone's part. I just wanted to post  this in case someone else had the same  problem.  The solution is pretty simple.

- Jeff
The Adventures of Capt Sanchez
Cybernautic Studios