Jay-d can't play songs

We just assembled jay-d and started testing it.
Unfortunately original SD card was physically broken so I had to use another as the replacement.

It was formatted as FAT and I prepared files as described in AAC, 64k, 24khz, mono.

Files were recognized by device, but it doesn’t produce any sound at all while playing tracks (boot sound and sound in setting for volume are OK) - neither in DJ not in Playback modes.

Here is the short video, describing the problem: https://youtu.be/7oqs9xZ5lXk

As you can see, device is able to produce sound generally, but it not producing any sound while playing tracks.

I’ve contacted support already, but so far didn’t got any useful information, except this link
which, unluckily doesn’t tell anything about SD card requirements, such as:
size, SD card type, supported file-system, etc.

So i wonder if anyone from the community already faced similar issues with Jay-D.

Thanks in advance for any hints!

I found some track example in another thread First JAY-D Performance :)
and they working fine!

So it seems like in my case issue was not with card, but something specific to tracks audio properties or their file names…

I’ve started comparing my files ( prepared at https://audio.online-convert.com/convert-to-aac ) and i found that seems this converter doesn’t actually converting stereo to mono.
So i’ve tried this
ffmpeg -i stereo.aac -af "pan=mono|c0=c1" mono.aac
on prepared files, but still Jay-D wasn’t able to play them.

Maybe there is some limitation for length of tracks?