Captivate embedded mp4 videos don't play on iPad and not on safari - how can we make them play?

We are using Captivate 9, and Captivate 2017.
Export is: HTML5 to SCORM 1.2.
We have embedded mp4-videos by embedding the files into the project.
The SCORM project is played on an LMS.
Result:
The videos play fine on any windows-based browser. The videos play fine on MacOS on Firefox.
The videos DO NOT play on MacOS Safari, and they DO NOT play on iPad/iPhone.
However, when playing the pure single mp4 file on iPad/iPhine (NOT embedded, just playing off from a filesystm like dropbox), the videos play fine.
So we figure, the codec of the video is ok - but how can we make the video play on iOS when embedded in SCORM?
Thanks for your help,
Alexander Stork