I have had problems with a few albums where I could not identify the source of the tag data after scanning new additions into the LMS library. I eventually tracked it down to a non-standard tag name in the original .flac files. I am using MediaMonkey to rip CDs and their automatic tagging occasionally (yes, go figure!) produces a tag labelled "ALBUM ARTIST" with a space, rather than the standard "ALBUMARTIST". The LMS rescan library routine cleverly treats them both the same. I am not sure that it should. Should it not ignore a non-standard tag?