Hi, Ive just fixed this problem, it is caused by null characters within the fields being compared with musicbranz (e.g album,artist,title). On Windows these characters are displayed as a square, on OSX they are invisible, they are generated incorrectly by some tag editors/players - with Itunes being the main culprit.
You can remove them in Jaikoz by running the AutoCorrecter or the appropriate Local Correcter (Local Correct/Correct Artists, Local Correct/Correct Album …) and making sure the setting ‘Remove Undisplayable Characters’ on the AutoFormat tab is checked. It is enabled by default for all columns except the Album column (this is a bug) so you need to go to ‘Action Settings/Local Correct Settings/Album Settings/Auto Format Tab’ and enable it.
If this does not fix your problem, please send me the file.
In the new release I am going to handle the null terminator characters before the records are displayed, and if you modify the tag they will be removed on save. This is ecause the advantages of displaying them so that you have an accurate view of what is being stored is being outweighed by the disavanatges.