audio drops

I'm using win 10 with the latest updates
resolve 15.0b5
And a rme fireface ucx for sound

I get about 10 seconds of audio in my resolve 'edit workspace' timeline before it drops.
Sometimes setting the bit depth to 16bit fixed the problem ... sometimes it doesnt

Sometimes i see the resolve meters working even though no sound comes out of my speakers
Sometimes the meters will cut out as well even though there is audio in the timeline

Video file is a 30 minute h.264 mp4 with aac audio at 48KHz 16bit

Additionally Windows randomly resets the bit depth to 24bits

-- playback simply doesn't work at all in the fairlight workspace
-- if I view the same timeline in the Media page i get sound all the way through the cut

-- attempting to render the project cause resolve to hang

Seems theres a problem with the mp4 wrapper

I transcoded the footage to low res h264 .mov and the audio was fine

Don’t transcode, just rewrap or you have a massive loss of quality.
If you’d rather transcode, use ProRes or DNxHD.