USB port now unavailable

Facts.

I have an iMac with Mojave (10.14.4).
The last system upgrade occurred about 4 weeks ago.]
I am using Arduino IDE 1.8.9.
I have previously programmed Uno, Mega2560R3 and Feather MO with this setup.
Until about a hour ago, there have been no issues with this setup.

Up until about an hour ago.

Starting with a new instance of the IDE, I plug in a MEGA2560R3. I select the correct board type. The port then tells me that I am connected to "/dev/cu.usbmodem14151201". I then upload a sketch and it executes. Board connecttion is USB type B

I then unplug the MEGA2560R3, plug in a Feather MO and select the correct board type. The port tells me its connected to "/dev/cu.usbmodem14151201" ( I THINK there were the same numbers but can not be 100% certain. Board connection is Micro USB type B

About one hour ago.

Starting with a new instance of the IDE, I plug in the MEGA2560R3 and select the correct board type. The port comes up with, as above, "/dev/cu.usbmodem14151201". Upload, execute, etc.

Now, I MAY have not disconnected (I can't be sure) the MEGA before switching over to the Feather MO. I plug in the Feather MO, select the correct board type and the ONLY selection for the port is "/dev/cu.Bluetooth-Incoming-Port". The previous port of "/dev/cu.usbmodem14151201" is not displayed.

Cables that are in use when the problem occurred are the same cables that have been used for the last several month. I've done the computer reboot a couple times. I've restarted the IDE several time, always with the same result - the MEGA shows up with a usb port available but the Feather MO does not.

Any ideas on what is happening would be greatly appreciated.

Currently depressed...

Strange. Has the system been rebooted since this incident occurred? I would try that, first.

Try this:

Problem solved. I fried the board!! Trying to determine how that happened but thats what happened. Just attached a new Feather MO and it is recognized without problem.