Audio issue

Has anyone experience this problem before? Everytime I import sound on the timeline, the first second of the waveform show but the rest of waveform is just a flat line. I mean, it still plays music but the waveform didn’t show. It’s really frustrating. I tried the QuickTime method, it didn’t work. (I’m on Toon Boom Harmony 20 btw) It’ll be nice if ya’ll help me. Sorry if my explanation is confusing.