Internal player of M110 - Video files random classifying

Here is the description of our problem :

It is relative to the use of the internal player of the M110, by using it with a microSD card or USB key.
We upgraded the projector to the latest firmware available on the Dell's website, to get the recognition of directories in the video files explorer. We meet a problem with the display of video files list : when we deposit video files in a sub-directory (example "/folder1/subfolder1"), they aren't classified in alphabetical order but in a random way. When we deposit the same files in the root ("/") or in a simple directory created in the root (example "/folder1/") of our microSD or USB key, the problem doesn't appear.

Projector FW : M0R003
Media FW : A56
Image Processor FW : M13

We use these projectors for professional training in countryside of Cambodia and we would like remove this trouble.

Thanking you in advance,

Mr. Schoellkopf Ugo, Phnom Penh