A slight guess here... And someone may correct me...
The issue is the radio is blissfully basic. It's software and processor has the power of a low end calculator, with a radio, bluetooth and mp3 player cellotaped on the side. It is what it is, and it's likely to keep working when all other head units are dead. Even when the 'bolt on's' fail, the head unit seems to keep working - showing how they've added stuff onto an older framework, just updating firmware.
On inserting a USB stick, the player will search for playable media, and then engage it. Asking it to do anything other than this (Like accessing a folder) could be asking a little too much.
A user manual (for the CD version) says:
The radio with MP3 player:
❒ recognises only the folders that contain MP3 format files;
❒ if the MP3 files on a CD-ROM are structured in "sub-folders", their structure is compressed to a single level structure where the "sub-folders" are taken to the level of the main folders.
It's talking about FOLDER compression (admittedly for CD's) rather than AUDIO compression , which is possibly because this system couldn't handle managing too much, it was a processor which was likely to be archaic. And the more modern system, which looks the same, is also likely to be outdated.
My experience of the AUDIO compression is that it is very poor. Fine for listening to the radio, but, really not studio quality audio (Nor should it be!), but, we're not looking at a music connoisseurs dream.
The user manual for yours is clear 'random' is possible:
MEDIA MODE
Press the "Select Source" graphic button to select the desired audio source from those available: USB and Bluetooth®.
WARNING Applications used on portable devices may be not compatible with the Uconnect™ system.
After Media mode is selected, the following information is shown on the display.
At the top: information on the track being played and the following graphic buttons:
"Repeat Song",
"Repeat All" or "Repeat Off": repeat the current song, all songs or turn the function off;
"Shuffle": to play the tracks in random order;
Applying old skool digital audio handling rules may help though, and out of curiosity, try naming the folders in sequence, i.e 0001, 0002, 0003. I have a sneaky feeling, for no logical reason, this may help. In the early of handling audio files, folder names really mattered. I'm wondering if this may be the case with your mission...
).
