Update... I solved the problem on the FT-891 running FT8 on WSJT-X with the help of a few ham friends, Brian NT7Y in particular. First, I uninstalled the USB Audio Codec, rebooted, and installed the codec fresh. Suddenly the software could hear the radio. But I still wasn't getting many stations. Another hint was to check the WDH (width) setting. It was set to 500 (hertz, I assume). I expanded that to 3000 and now the radio works perfectly. I picked up another dozen or so FT8 QSOs last night to make sure it was working right.
Update... I solved the problem on the FT-891 running FT8 on WSJT-X with the help of a few ham friends, Brian NT7Y in particular. First, I uninstalled the USB Audio Codec, rebooted, and installed the codec fresh. Suddenly the software could hear the radio. But I still wasn't getting many stations. Another hint was to check the WDH (width) setting. It was set to 500 (hertz, I assume). I expanded that to 3000 and now the radio works perfectly. I picked up another dozen or so FT8 QSOs last night to make sure it was working right.