Got the answer. It was a Mac display resolution issue. When I changed from “Default for display” to “Scaled” and chose the icon just to the right (“More Space”) of the Default, the jog control buttons appeared.
When using “Default for Display” with a large external monitor connected, the jog control button is visible on the large monitor, and not on the MBPro.
Thanks to David Weiss for talking me through this. No substitute, sometimes, for two people on the phone trying the same thing on different Macs.
Resolve 12.5.2.010
MacBook Pro mid-2014
OSX 10.10.5