Audio Waveform Not Showing in After Effects Timeline

I do the kind of program you are describing all the time. I take a shot with a spokesman or interview, or a narration track and combine it with motion graphics. The master shot or audio track is usually broken up into sections with markers in Premiere Pro for video or Audition for audio, and a separate comp is made from each section. Occasionally I'll break up a master shot in After Effects, but I almost never render the master, I only render the sections.

I've been doing this for a very long time. I know that it sounds like more work, but everything is easier to handle and you'll get finished in less time. I don't think I have ever had a single AE comp longer than a minute or two in the 25 years. A few years ago I produced 6 hour-long programs for a national client that was 100% animation. Every frame came from After Effects but not one of those comps was longer than a sentence or phrase, they were all rendered and the edit was done in Premiere Pro.

Here's a current project composed of 4 different shots. The shortest Master comp from the 4 shots is 15 seconds long, the longest just over 2 minutes. Each master has been split up into separate comps appropriately named. The flow chart shows the 4 comps that I will need to open up in the Scene 3 section to make some changes for the client. The master timeline shows the sections of the shot that did not need any work. The render cue shows 68 renders so far with a typical render time of about 5 minutes. The longest render time was for Scene 1-05, a 9 second and 1 frame comp that took just over 40 minutes because it was very complicated. 

Just imagine if this project, with a total running time of just over 5 minutes was one comp. The comp would have several hundred layers. Drilling down to find about 75 or 100 total frames the client wanted to be changed in a half dozen layers would be a nightmare, and the project would take several hours to render. 

I'm just trying to help you work more efficiently. I would break up your comp into sections that were no longer than a single animated section before I did anything else. Even if you kept the Master comp a full 45 minutes long and never went to Premiere to finalize the edit, you would be a lot more efficient.

If selecting a layer with audio and pressing the L key twice does not reveal the audio waveform, try changing the first tab in the Project Settings - Video  Rendering and Effects by pressing Shift + Ctrl/Cmnd + Alt/Option + K.

Try changing the Hardware accelerate composition, layer, and footage panels by pressing Alt/Option + Ctrl/Cmnd +;  Then navigate to the display panel.