Yes, the latest UAD software. I get signal on input, as with an electric guitar, and I can record a track. The sound is loud and clear on input. But when I playback the track...no sound. I tried with existing projects, new projects, audio, MIDI, etc. I set the Apollo Twin to its default setting. All of these have the same result, no output. As stated in my original post, it is only with Logic Pro 10.6.1. All other apps work fine.