QT export; No Sound

I’m new to Harmony and using v20. I animated my first shot freehand after importing an animatic clip on a layer. I was able to scrub the sound and the export was smooth. The sound played great. I’m animating my second shot and the QT export isn’t playing sound. I’ve rebooted, relaunched and gone through the prefs again to make sure I didn’t accidentally change anything, but it all looks fine. The dia plays fine in the program on playback. Thoughts?

I changed the output from mp4 to QT Movie and the .MOV exported the sound. My previous successful export used the mp4 option, so why it worked then and not now is a mystery.