The #EXT-OATCLS-SCTE35 tag (and the #EXT-X-SCTE35 tag) are not recognized by Apple parsers. They will be ignored as comments.
The only Apple supported way of including SCTE-35 data is via the EXT-X-DATERANGE tag with the various SCTE35 attributes.
The daterange tag was made public with draft-pantos-19 and is supported in iOS 9.3 and beyond.
See the spec for the details - https://tools.ietf.org/html/draft-pantos-http-live-streaming
See also the WWDC 2016 video - What's New in HTTP Live Streaming - https://developer.apple.com/videos/play/wwdc2016/504/ which talks about the various ways metadata can be included in HLS streams.