Source monitor is not displaying audio waveforms

I am currently working in Premiere CC 12.1.2. I've merged a video clip with an audio track. I've then pulled subclips from this larger merged clip. When I work with my subclips, Premiere will not display my audio waveforms of my subclips in the source monitor. It only shows large grey bars. When it finally does show the waveforms it only does so while the video is playing and then disappears again once I pause playback in the source monitor. The waveform also vanishes when I try to zoom in on them in the source monitor. Anyone know why it is doing this?