Right, well that was a total disaster but I think it may be getting us closer to the source of the issue.
Here’s a screenshot of 3 different views of the SD card’s content according to Windows:
The first is of the root. Note, there are no .update or .smb folders. device_trees and LOST.DIR are both empty. Top right is the contents of the Android folder. Each one if its subfolders have a sub-directory called ‘files’ and they are all empty. Finally, on the lower right I opened the empty ‘files’ folder under videolan and pasted a file ‘friller.mp4’
Next, I returned to the home cinema and ran CoreElec again. Nothing we can see in the windows screenshot can be seen in CoreElec’s file manager without digging very deep and even then, the friller.mp4 file remains invisible.
So, I’m guessing that either Windows is unable to view the contents of Linux, OR all the directories with storage and databases shown in CoreElec are actually stored on the AM6’s internal memory rather than on the card itself.