For the longest time I just assumed this wasn't possible because I've never seen a waveform for a nested sequence.
However, tonight I just saw one of my sequences with an audio waveform! AWESOME!
So, apparently, this IS possible? How did I get a waveform to appear? I'm not aware I did anything, but obviously I have a waveform there, so I'm wondering if I hit some secret keystroke or pushed the magic button somewhere. How did I get that?
As you can see in the other comps on the left, they are behaving like I've always seen them behave--with no waveform.
Apparently the nested audio got rendered (Sequence > Render Audio). It's very easy to test out.
Best Thumbnail Ever.....
and rejdmast1 is right. It is a very quick process on my system.