Would it be possible to send me (privately) the audio file?
If not, does the error appear immediately or later in the computation? Does a lip sync take still get created? Can you provide more specifics about the file (e.g., AIFF or WAV, stereo or mono, sample rate, etc.)? If you select the audio file in the Project panel, the Properties panel should show some of this info.
For some reason it won't let me record actions for the entire audio file, it cuts off at a certain point (the dimmed out section on the right in the timeline).
A lip sync take is created but it doesn't play all the actions I record. I recorded two separate arm movements and a head movement but it only plays one of them at a time.
The lighter colored background in the Timeline panel represents the scene's duration. The Compute Lip Sync from Scene Audio processes the audio within the scene duration. To change the scene's duration, select it in the Project panel, then adjust the Duration value in the Properties panel.
For recording multiple mousetracked handles, try adding a second Mouse Tracker behavior. See this topic for more info: different takes of mousetracks
I'll e-mail you directly with something else to try.
This issue should be fixed in the upcoming Preview 2.