We applied some CSS styling that were requiring the Chrome Web Browser to be in Emulation Mode. The problem when you emulate a Mobile Device in the Browser, is that the filesystem used by the App to store/retrieve content is then completely different. The App will no longer be able to create and retrieve files.
Lesson is: Be careful if you have to use the Google Chrome Device Emulator in your development phases. MobileMoodle use the Browser FileSystem API to store files (files that are actual Course materials). When you enable the Emulator, you completely confuse the Filesystem API which seems to not be able to retrieve what has previously been created.