We are using Presenter 11.1.5 and publishing to HTML 5.
On Windows computers we have tested in Chrome, Edge and IE 11 and everything is working fine, when we press the play button on the first slide the audio starts playing.
On Mac OS/X and Safari the play bar shows buffering and stays like that no matter how long we let it wait. If we push Play the audio does not play. If we click on Rewind and then Play the audio plays fine.