Help: Gumball disappears!

[jch51502]

Same thing appears to have happened here to this user:

Strange gumball behavior

Most of the time when I click on an object the gumball flashes (appears for a microsecond) and then disappears. To make it reappear, I have to zoom in or zoom out from the object (with the mouse wheel) – then it reappears and stays so I can use it. Just wondering… is this a normal part of 3d modeling or do I have some kind of setting that I need to adjust? Does anyone else encounter this? (I am running Rhino 5 with Windows 7 – 16 gb ram)