Oh well..Here's how to replicate.
1. Get foo_cwb_hooks and made a masstagger script like this thread and set "new file tagger" option in preference to use this on files newly add to library.
2. Create autoplaylist out of some folder from media library using either new albumlist or with 0.9.5.1 beta, the new "Media library search" and convert it content to some another format to the same folder. Autoplaylist will update it content in a strange way (add double or more entry) and if you restart foobar, the newly convert file which first show in playlist (but with duplicate entry) will simply vanish from that autoplaylist.
Using the old autoplaylist to do the same thing by using query to moniter folder (like %path% IS *\rock\*) don't have the same behavior. It working like it should perfectly. Using the same query to create autoplaylist by the new "Media library search" in 0.9.5.1 beta have problem mentioned above.
This happen since 0.9.5 beta and still with 0.9.5.1 beta. I'm a bit reluctant to report this since it has 3rd party plugin involve and masstagger is not support anymore
but as I see that with the old autoplaylist it work fine, something maybe wrong here so I reported it. (but I don't know what exactly cause the problem, cwb_hooks or new autoplaylist or somewhere else.)Regard