how come my audio and waveforms disappear when I press the proxy button?

[rachelcenter]

i have an MXF clip on my timeline and it has waveforms but when I press the proxy button the waveforms go away and that clip doesnt play audio any more. why is that? i think the format of proxy i chose was quicktime prores medium resolution.  you can see i have 2 clips stacked on top of each other. i think both have the same format of proxy. but the audio isnt disappearing for both clips. only one clip. the audio shouldnt be disappearing at all when I turn on the proxy button.  Meta data for the clip with disappearing audio says the camera type is Sony PXW-FX9V.  video codec avci.

  

[Ann Bens]

Guessing the proxy files have but 2 tracks.

You can check this with Mediainfo or import a proxy file to see the metadata.

[rachelcenter]