Thanks for your quick response!
I copied and pasted the "OS X Yosemite v10.10.5, OS X El Capitan v10.11.6, and macOS Sierra 10.12" update title from my update list. I'm guessing Apple set it up to update whichever of the 3 systems you might have, and my computer selects which update it needs? I don't know. I have El Capitan on my iMac.
Snapz Pro X automatically notifies me of updates when I'm using it. It won't start at all. I didn't see anything on the developer page, but I didn't spend much time there. I'm guessing since the Apple update was just yesterday, they haven't had much feedback yet.