The audio should come in automatically once the video file is selected, since it has the same file name as the video.  It has always worked that way in the past.  Not doing anything differently than what I have done for the past several years.

I checked the options in Preferences to make sure the box was ticked that says to link video & audio files with similar names - it was ticked.  So, no rational explanation as to why the audio will not play.

Yes it should work that way, but since it doesn't, rather than fight it you can bring it in manually. Sometimes software fails.

I have tried to bring it in manually and that does not work either.  It says it is "Building peaks" and then when it gets to 100%, there are no audio wave lines on the audio track - just straight lines.

Can you play the audio track in other software like VLC? There might be something wrong with the track itself.

It will not play in VLC.  My other project ac3 files do play ok in VLC.  So, perhaps Vegas Movie Studio 15 is not correctly encoding the ac3 file when I do the audio render.

You may have noticed that the AC3 audio is called Studio File. It is a non-standard AC3 file. Your previous versions might have used AC3 Pro which is the licensed standard encoder. I don't know if this is the problem, but it could be. I have never used AC3 Studio so I don't know if it works okay. Magix did not relicense the AC3 Pro encoder when it took over the Vega line.

Are you using the latest builds (currently MSP 15 b 116 and Vegas DVD A b 84 or at least 67)?

Using: Movie Studio Version 15, Build 102 & Vegas DVD Architect Build 84.

One other comment I should make.  When I first got this new software, I created one movie which did load the audio ok in DVDA.  However, for every new movie that I have made since then, the AC3 audio rendering will no longer work in DVDA.

The AC3 Studio template should work fine in DVDA since the movie making & DVD making software were sold as an integrated package when I purchased VMS 15 Platinum.

Update:  I just updated MSP 15 to Build 116, re-rendered the AC3 audio file and imported the video & audio files into DVDA and the audio track now plays fine during the Preview in DVDA.

So the Movie Studio update seems to have cured the problem.  Must have been some sort of corruption in the old Movie Studio Build 102 that was causing a problem with AC3 rendering.

Thanks for the tip to update, I was not aware that a new MSP15 build was available.

The AC3 Studio template should work fine in DVDA

As you can see from my screenshot, it is possible with the current builds at least. There were initial difficulties with early builds of MSP 14 and DVD A. You might try updating MSP 15 to b 116 and then maybe resetting DVD A.

Well, I spoke too soon.  I just made a small edit and re-rendered both the video and audio.  Now the audio will no longer play in DVDA.  The re-rendered AC3 audio does not play in VLC either.

However, I find that if I render small segments of the overall audio file, some of those small segments (loop regions) will play in VLC while others will not.  Makes no sense whatsoever.

Another Update: Some more experimenting with my MSP15 project.  When I render a portion of an mp3 file, or the audio track of an mp4 file, or a wav file, to AC3, it will not play in VLC.  When I render a portion of an mp4 audio file, or an MPEG-4 audio file, to AC3, they do play in VLC.  I do not have the technical knowledge to understand why this would happen.

So, MSP15 seems to be the culprit, not DVDA, i.e., MSP15 appears to have some type of corruption in the AC3 rendering process.

You may be on to something!  I re-rendered the entire audio track to a different name (rather than over-writing the old file name) and the new file now plays fine in VLC & DVDA.

Wonder why over-writing the old file name would cause it not to play in an AC3 format?