That's very goofy! Have you tried a different mouse? I went out a piece-of-crap $12 wired 3-button Kensington optical mouse (which had the very clever model name "Three-Button Mouse"), and it's been flawless and perfect. And I've used every pointing device known to man in the past 30 years, including trackpads, pointing sticks, trackballs, 50 different mice (meeses?), and tablets. Works great under OSX with Resolve. I thought I would go back to my Apple Magic Trackpad for everything else, but I've gotten so used to the stupid cheap mouse, I'm still using it, months later.
No issue with middle-button copies or viewer repositions or anything.