Hi forsuretheone,
The EOS Webcam Utility hasn't been updated for OS12 yet, so it might not run properly on that operating system. There is some trouble shooting to try. The first is to restart your computer. The EOS Webcam Utility needs a computer restart to finalize the installation. Make sure you are selecting the Restart option by clicking on the Apple icon in the top left of your screen rather than using the power button on the computer.
The other thing is to make sure your EOS Utility is fully closed before starting your webcam software. When the EOS Utility and the webcam utility are both on at the same time it prevents the webcam utility from detecting your camera. That is because when they're both open at the same time they both try to use the camera at the same time. When closing the EOS Utility make sure to select Quit from the top menu rather than just closing the window. That way it isn't running in the background.
One more thing to do is to make sure your camera is set to Movie mode. Sometimes if the camera is still in photography mode it can cause connection issues. Along with that if the issue continues try unplugging the camera from the computer, turn it off, take out the memory card, close the card door, turn back on the camera and check to see if the same thing happens. Sometimes software on the computer detects the memory card on the camera and tries to access it as a drive. When that happens it would cause the same sort of conflict as the EOS Utility. Taking out the card is a good way to get around that and the EOS Webcam Utility doesn't need the card to be loaded so it won't cause an issue there.
