to recap: using High Sierra, WSJT-X stopped receiving audio on a USB port on my MacBook Pro though other programs (JS8CALL, fldigi, cocoaModem) do. WSJT-X does transmit using the same USB port without issue. Yesterday, I took an external HD which was cloned from a desktop computer of mine running High Sierra, booted from it using the MacBook Pro, and installed Mojave. WSJT-X and the three other digital programs worked OK. Encouraged, I upgraded my MacBook Pro to Mojave last evening and immediately learned that WSJT-X still does not "receive", while the other three programs work fine. So this eliminates hardware and High Sierra versus Mojave while leaving some HD-unique items such as Preferences open for discussion or solution.