Unfortunately, the OS update did not fix my problem. But it has perhaps gotten me closer to a solution...
After my OS update, when I first plug in the SkyRadar after the iFly software is running, if I check Menu>About>Connected Devices, there is no immediate change. However, after a few seconds, when I again check Connected Devices, it will say something like "Discovered Serial Ports: '0', '1'", and below that it will say, "Controller Status: / --------------- / Settings: None / Active Ports: 0-9600: 1-9600". (It will actually repeat the "Settings / Active Ports" group of data for each discovered serial port.
If I check under Mode, the iFly always reports "Weather (Pre-Flight)". (I.e., it never reports that it's connected to an ADSB device.)
Over time, if I periodically check "Menu>About>Connected Devices", I will see the number of "Discovered Serial Ports" grow. For instance, right now the iFly has been on for ~30 min, and it has now discovered 14 serial ports. There are also 14 groupings of "Settings: None / Active Ports: 0-9600: 1-9600: 2-9600: .... 14-9600".
So, whereas with the previous OS the unit would recognize something was plugged into the USB port but couldn't find a driver for it, now with the current OS it appears that it is continually finding something plugged into the USB port but it is not establishing a good connection to and receiving data from the SkyRadar.
Shane or Ed, what's my next step?