This is exactly what was wrong for me too. As a matter of fact I have a logitech muse and keyboard combo on my mac and a Wacom tablet. I've spent all day today diagnosing the problem. Who would have ever thought it was a simple as a mouse, or tablet issue ! Thank you so much. FYI, I didn't need to do any of the terminal stuff - I just unhooked my USD dongle and cables and used my trackpad - and it all worked.
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