I use After Effects CS6 with a pretty new i5 desktop computer with Win8. My green audio bars (not sure of the technical name) just starting being invisible for the first time, so I can't edit/move them around anymore, as shown in this screen capture here:
(Sorry if it's small, Photobucket shrinks my image files if they go beyond a certain size, but Ctrl++ may help to zoom in for details.)
You can see how the green bars are missing even though you can still see the accompanying green Waveform underneath where the green bars should be.
Why did they disappear and what can I try to do to reclaim the green audio bars? I also can't seem to continue the project until I get past this issue, as even putting in new audio bars show up as invisible. (It's as if the project file has 'had enough' and wants me to start a new project file, but this would result in repeated work.)
(I feel like this started happening because the project got too big for one file, due to being 12min long and having 337 'layers' so far, but I don't want to suggest that as part of the answer, I'm just giving my own inexperienced feeling about the matter. Plus, I already tried dividing the project up into two 7min halves, since I only started having this problem at the 11.5min mark, and, unfortunately, the new second half still doesn't even show the invisible green bars, despite being only 7min long instead of 11.5min. I also notice performance issues replaying the entire thing with a RAM Preview after it got to be around 11min in total, with random audio skipping and the like, making me assume I'll keep projects to about a 7min maximum from now on to be safe and just compile them all afterwards. Another performance issue is that it clearly doesn't complete the RAM Preview distance that is set. Instead it stops where it wants to and commences replaying.)
Edit --> Preferences --> Media and Disk Cache --> Purge. And you might wanan consider substituting any compressed audio sources with WAVs, too, to avoid such corruptions. Similarly, check your audio in a proper audio editing app. Odd sample rates, weird channle mapping and so on can have all sorts of ill effects.