IVS Playback from Cloudfront

Hi I have successfully setup IVS to LiveStream from OBS (Open Broadcaster Software) and to record the stream into an S3 bucket. This is all working Ok in terms of live streaming. I have followed the Amazon article to enable video on demand playback from Amazon CloudFront. I have located the object key path for the master.m3u8 that it created and appended it to my CloudFront URL. However it does not play anything at all. I have put the URL into the Amazon IVS PlayerSDK in Chrome and also saved the file and tried to play it via VLC. I get no error messages just a black screen and no time line, so if I click the play button nothing happens. Cant seem to find out why its not working? Many thanks Mark