Submitted by Bill St. Clair on Tue, 18 Oct 2016 06:51:14 GMT
I've been having a problem with my late 2011 iMac. I wrote about it back in April, in Mac OS X 10.11.4 Beachball on Wake from Sleep. With my upgrade to macOS Sierra, the problem has changed. It no longer beach balls, but it wouldn't wake from putting the display to sleep (which I do with a hot corner in System Preferences / Dekstop & Screen Saver.
I discovered a month or so ago that momentarily pressing the power button, on the back left corner of the iMac, wakes it up. I've been very happily using that since then. Today, I discovered that clicking the mouse button also works.