Earlier I tried to add an entire album of FLAC songs to the queue from the Library tab.  GMB added them to the queue then immediately removed them from the queue and the Library tab. The album and song count reduced in the search feature and the songs (nor the album) could be located using search (even after GMB restart). I had to drag the files from Thunar into GMB's queue to get them to play. Subsequently the album and songs returned to the library tab.  Any ideas as to why this happens and how to prevent? I am using the latest GIT version, 1.1.9.2, according to the about.

Thanks

Most probably, it's because the file were renamed or moved, when it tried to play them it checks if the file is still there, as it wasn't it was removed from the library (can be disabled with the option "Automatically remove current song if not found"), tried to play the next one ...
Currently, only move/rename made from within gmb update the library. I plan to add support for watching files (inotify) but even then if the move/rename happen when gmb is not running, there is no way for gmb to know the new path/filename.