this is the most time consuming bug I have yet to personally encounter and it is a bug
I have encountered the same behaviour in Europe at 25fps and I am old enough and wise enough not to mismatch frame rates or audio sample rates
it is a pure bug and apple had better fix it
cos it has sucked so many hours away from my workflow
right when you are trying to render out the final master of your project, with all edits finished and audio mixed
you get a phantom sync problem
its ridiculous