Audacity convert 5.1 ac3 to 5.1 wav

I have tried this & so far it is not working.
I just get a 4 minute .wav of a 2 hour .ac3 ripped from a concert DVD.
Both are 5.1 .
Anyone know how to get Audacity to do the complete 5.1 .ac3 to 5.1 .wav ?

I have other software that can do this but I don’t know why Audacity doesn’t or can’t.

This is what I’ve done.
I installed the latest Audacity 2.0.3
This is the odd behavior I can’t figure out.
The .ac3 file was ripped from a Woodstock concert DVD.
It is 5.1 & the legnth is 2 hours 8 minutes 39.744 seconds or 128minutes 39.744 seconds .

I open this .ac3 file in Audacity .
I am trying to convert it to a 5.1 .wav file .
If I select the total time on the .ac3 file I get a 5.1 file that is 4 minutes 16 seconds.

If I select a little less than the total .ac3 file for example 128 minutes 36.668 seconds .
That amounts to only 3.076 seconds .
With this file that part is only audience noise so could be cut .
It might have been music that I would have wanted that is why I wanted it to work with the whole file.
With the slightly shorter selection I get a 5.1 .wav file of the selected legnth of 128 minutes 36.668 seconds. The size is 3.8GB .
That means it could only be burned to a DVD . Or divided & burned to about 5 CDs.

I wanted to know if anyone else has tried a similar conversion & had success.

Also I don’t have a 5.1 stereo so I can’t test an Audio CD burned with a 5.1 channel .wav . Does anyone know if it would work playing all 6 channels ?