Sometimes the spectrogram will not repaint a certain part of the window. Specifically, it's the right side of the spectrogram window. Scrolling through the recording will result in this part of the screen still not repainting, essentially hiding the spectrogram behind it.
See the attached image for more information.
This bug seems to be the result of making a recording, as it didn't surface with Formant Synthesis.
Spectrogram not repainting on the right