Tools-Port works fine for IDE 1.7 but is greyed out in 1.8 on Apple OS 10.11.6

For the same UNO and USB cable, Arduino IDE 1.7.11 shows the serial communication ports and uploads work fine, but with a new install of Arduino IDE 1.8.1, the Tools->Port is greyed out.
My Apple Mac OS is 10.11.6.

I have tried connecting, disconnecting the USB cable, and closing and opening the IDE. The Port continues to be greyed out for IDE 1.8.1.

Thanks in advance for any suggestions.