If you don't get a response to the email use the CHAT feature. https://www.nch.com.au/support/regcontact.html
Again, what are the PC specs? CPU/GPU/RAM? Have you downloaded this as protection, so the server can be cleared?
The issue is baffling as it can't be replicated by Nat or me using versions 8.10, 8.12. or the latest beta.
Is there no audio from the sequence only after export or is it missing as you are editing as well - played in preview?
If the latter, confirm the volume slider is to the far right and that no clips are muted. The track should like the image below for every clip...
There should be no RED X on any speaker icon.

Click on each speaker icon. In the box that appears, be sure that the volume slider is far RIGHT. 
Last ditch efforts...
Clear Unused Cache Files, under OPTIONS | DISK tab.
Do a full UNinstall, using this free tool. Then reinstall the latest version.