Mac often perceives left-click on Magic Mouse as right-click
Update:

I randomly noticed that a three-finger-tap on the built-in trackpad would not pull up the dictionary entry for the selected word (like it used to).

I navigated to:


System Preferences → Trackpad → Point &amp; Click tab → and saw that the "Look up &amp; data detectors" checkbox was not enabled. 


This was very strange, because this feature has always been enabled, and I never disabled it. I enabled this checkbox, and the "look-up" feature now worked.

But, this immediately made my computer stop perceiving all right-clicks (i.e., right-clicks on my mouse were always perceived as left-clicks).

So, I navigated to:


System Preferences → Mouse → Point &amp; Click tab → and toggled the "Secondary click" checkbox off and back on.


After doing this, my computer has not perceived a left-click as a right-click again.

I still have no clue what caused the issue, or why doing the above solved it, especially considering that, for good measure, I had already previously deleted the com.apple.AppleMultitouchTrackpad.plist and com.apple.driver.AppleBluetoothMultitouch.trackpad.plist preference files.