There have been several similar reports of late, but the audio loss can not be replicated by NCH or the testers in this forum. That's the case with both of your projects.
Using version 8.23, they loaded and exported normally with audio intact. For a short while, here is the result of the video clip. Click DOWNLOAD to save it to your PC.
What are your PC's specs: RAM/CPU brand and #. To see this, click the Notification icon at the bottom-right of the Windows 10 screen. Click ALL SETTINGS | SYSTEM | ABOUT.
Can you test Videopad on another PC?
Try closing Videopad, then restart it and before loading anything Clear Unused Cache Files, under OPTIONS | DISK tab.
If that makes no difference, try a total uninstall using this free tool. After it runs the Windows uninstaller, select all the registry files that it finds and uninstall those as well.
Then reinstall Videopad.
A note has been sent to the developers. Please report your findings here after trying the above measures..