Cover art issue with ogg files

I encounter a strange behavior, all my local .ogg files prevent the cover from being displayed in the web interface.
However the image appears well on the pirate audio display…
I don’t have any problem with FLAC or MP3 files…
Does anyone have an idea?

Maybe someone could tell me how to “send” pirate audio cover arts to mopidy cover art?
Thanks a lot.

Ok, I found a workaround by using MusicBrainz to download cover picture in the directory.