XDJ-AZ E8305 with certain mp3's that DO work on XDJ-RX3 & rekordbox

I have a bunch of 320kbps, 44100Hz mp3's which have been playing without issues on my XDJ-RX3.
I bought an XDJ-AZ and it refuses to play a couple of files, especially my own remixes it refuses to play.

If I compare a file that works and one that doesn't work I can see that there's another encoder used, and that the file is not original.

So my first guess was that the problem is the way of encoding by my remix program.

The funny part is that if I take a file that works, and re-encode it with my remix program, the file still works.

I'm out of idea's, clearly it's not an encoder issue or tag issue, but something else which is cause the AZ to trip with some files.

It's not USB error eather beacuse when I try to play the file via the wifi link mode, I get E-8306

What is going on here?

kind regards,

Nick