Can't see the waveforms

[Apteryx]

I cannot see the waveforms on something I record.

Input levels are good and playback is fine, excepting its appearance is blank. The track is set to "waveform". I do see a waveform when I zoom so only three seconds of audio appears on scren, but it goes blank if I zoom out at all. Adjusting the height of the profile display and the track height seem to make no difference. What am I missing?

PS I checked FAQ and searched the DUC before posting this.

[Apteryx]

So I created a new session. Same thing. Then the Mac crashed. When I got it running again, the problem was gone.