Unfortunately, the new .braw codec is being overlooked by Adobe and can be ‘buggy’ and temperamental, more than likely you will need to transcode (or repackage) the .braw footage into something more user friendly, if you are working on a Mac then the best codec to transcode to is Apple ProRes 422.
You will need to do this in Davinci Resolve as Adobe Media Encoder won’t recognise the codec.