Yes you get the error log and send it.
At the latest release the search happens on MusicBee.
I just generate an XML like the one used with the Auto Playlists and I pass it to the MusicBee API. Then the API returns the matching results (so it could be an issue there maybe sending something wrong to the API). It will not be the same on the version under development though.
If you have the same issue with the Auto Playlist matching, then it could be a MusicBee issue and you should report it to the bug reporting forum. If the Auto Playlists work properly, then the issue is with my code. So if the existing logging functionality isn't enough to reach a conclusion, I will have to add logging to a few more parts, in order to figure out why that happens.