Follow up for those who might find themselves in a similar situation:
It appears to me that the configuration files from previous versions of the app are not compatible with the new v2.20. I had to manually reenter the station name and ip address:port for each of my stations, but now we’re back to familiar territory. Not too bad; as long as you have that information easily available. 😉
I might have been able to import the configuration from an earlier version’s exported config but I didn’t try. It ended up being easier to re-enter each station’s name & ip address than to find that old config file and then drag-n-drop it into the app’s Import dialog.
Maybe someone else can confirm whether or not their pre-v2.20 config file will import into v2.20.