First of, I am not sure this is a problem in Jaikoz.
In the 3.x versions when I did a manual correct metadata from musicbrainz tracks either had or had not a checkmark in the Amplifind Id checkbox indicating an Amplifind Id match (or not).
In the 4.0.0. version all possible matches returned always seem to have the Amplifind Id checkmark.
That's not it i'm afraid. I have yet to see a possible match that does not have an amplifind id match according to Jaikoz and during the weekend I have checked several hundred songs. Even different songs from different artist claim to have the match. This can of course be faults in the musicbrainz db but I suspect something is not going quite right here.