I see you have connected with support and working with them.
In general a couple things to always check
1. Do the videos play when in Claro in Single page Preview and Full Course Preview.
- If they do play play in both single page preview and full course preview, but when you publish them to your LMS they do not play then it is likely an LMS or LMS server issue (server may not be properly supporting MP4). One way to eliminate that from the equation is publish it to SCORM.com (they have free test accounts) and try it there. If it works there and when in Claro - then most definitely it is an issue you need to contact your IT that handles your LMS.
The videos do need to be MP4. That being said sometimes the videos that are MP4 are not properly encoded. Also if you haven't compressed them, it is a good idea to do so.
(A great free tool, to both encode properly and compress is Handbrake - https://handbrake.fr/ - use the for web and size the video properly and then replace/update your video with the newly compressed item)