Mopidy local scan ignores some MP3 files


On a fresh setup of raspberry pi with Raspbian, I installed mopidy with one non-standard extension: Iris. After installation, I created a fstab file to mount USB drive with all my music to /mnt/media and specified that directory as a local media root in mopidy config.

After running the full scan, mopidy reports finding ~1800 files, but only ~1500 were added to the library. Admittedly, some of those files are not music - album covers, etc. But for some reason, the scan skipped past several folders of MP3 - the folder is visible in web interface, but is shown empty, while simple ls lists all the mp3’s within.

Could you please point me to the possible problem? I ran mp3val over my entire library and checked all the tags with EasyTag - they seem to be fine. I am lost as to where to look. Thank you!