Mono to stereo changes pitch in right channel

I have some clips that only have audio in the left track. I want the audio in both tracks, so I change the clip attributes to be stereo and select the audio track for both left and right channels. This works fine.

But if I save my project, exit Resolve 15.0.0B.057, then restart, the audio in one track plays at a faster rate. The left channel plays fine, but the right channel plays back much faster so it sounds like chipmunks.

Dee