Hello, and thanks for your replies !
The only info I have on the file is the file name. Which is the correct file, but with hyphens : "p18-somos-el-futuro.mp3". There is no pre-existing tag.
When I hit "lookup" it uses the file name (since there is nothing else), and finds nothing (hyphens don't help with the search query apparently).
When I hit "scan" it finds the AcoustID perfectly. But that's it. No additional info : no title, artist, etc. But the AcoustID found is correct.
=> I hit save to write the AcoustID tag into the file, thinking at least now it will have this info for the lookup, maybe it will use it. The AcoustID tag is correctly written into the file.
When i hit "lookup" again, still nothing. Same when i hit "scan". Even if the fingerprint enabled Picard to identify the correct AcoustID, which is linked to a MusicBrainz Record, it's like it doesn't go all the way.
Below is an example workflow in GIF (watch till the end, I lookup the AcoustID in browser) :