Only with HDMI monitor and enabled mirroring my mouse simply disappears. I have Mac OS X 10.10.5. I have to remove the HDMI cable or disable mirroring and then it appears again. Any ideas how to fix this?
It has apparently something to do with Accessibility.
Workaround: try changing the size of the pointer in System Preferences > Accessibility > Display:
- if you had set a bigger pointer, reset it all the way to normal,
- if you had it to normal, set it around ⅔ of the distance between normal and the first tick.