Just figured this out. The way to get waveforms to show up in Adobe Premiere CC 7.2.2 atleast is to make sure none of the audio clips inside the nest have any effects on them. Soon as you strip all the FX off of the audio clips in the nest you’ll see your waveforms again when you drop the nested sequence on a timeline. This was driving me batty but just dumb lucked into figuring it out today.
Cheers,
Jayson