cromano
Recently got X2 and not really happy with it. Locks up and gives a message about no audio when exporting. have to do it several times to get it to work. Probably a bug among many.
If you get a "No audio" message, the most likely reason is you haven't selected audio. Are you talking about Simple Instruments Track? Are you sure about your selection method?
When you jump 10 years forward in one go, don't expect things to be the same. I'm sure there are many things in X-series you need study almost from scratch, that's what the ones who upgraded from SONAR 8 had to do.
I assume you're using X2a, not X2? If not, do update.