No sound when exporting

Ok, here is my problem: I did recorded several files ( around 20), each one on a different track.
After exporting 5 of them I saw a notification about an error. Next I see the output on top bar in yellow and writing “not connected”
I get error about disk problems when I try to export again.
I did set the output ( I use a UR 22 MK 2 sound card) but now even I see the sound wave in the monitor next to the track, when exporting the file I have only an empty track, no audio.
I did restarted the computer but no changes. Any idea please?

Can you hear sound when you record the audio?
Did you check the settings for outputs?
In the audio settings, there is a place for specify outputs and audio options. Be sure to check those boxes.
Did you select the left and right ranges in the main window?

“not connected” usually indicates that one or more of your outputs haven’t been assigned in the VST Connections.
As benprusinski pointed out, Check your VST output settings and make certain that the outputs are assigned.
Whenever I’ve had the issue you’re describing it’s usually because the I didn’t have the appropriate audio bus on the left of the Audio Mixdown window selected prior to exporting.

A good rule of thumb (not absolutely necessary though) is if when you hit to export to mixdown, if you don’t hear the playback of the audio during the mixdown; chances are fairly good that your mixdown won’t have any sound either. But like I said, this is just a general rule of thumb to follow until you’re 100% comfortable with the process. It is NOT necessarily true in all circumstances but when troubleshooting this type of problem; I’ve found it to be a very good technique.

So for example, if you have a Stereo out track, a vocal track and maybe a guitar track that you want to mixdown; but you know the actual sound of those tracks are being routed to the Stereo out. You need to ensure you have the Stereo out track checked on the mixdown.

If you have sound during the mixdown of the audio, you can almost guarantee that you’ll have audio in the exported file.