I have a Galaxy S7 Edge, and am using the 64GB SD card they gave with the phone when it first came out at BestBuy's. I've put music on my phone already and have had it stored on the SD card and have never had an issue changing up what I have on there until yesterday. I re did my playlist and put different music on and synced my phone only to get to work and find out certain songs do not show up in the default media player (even though they are songs I've had on my SD card before). So today I decide to re sync it and after it is done I went through Windows Media Player and it said all the music was "Already On Device". Go to the default media player on my phone to a specific artist, and only HALF of their albums are on there... And when I say half I mean, it basically skipped every other song on every album. So half the album is on and the other is not... But when I search files on my phone all the music shows up.
I know there were other people with similar issues that I saw but none were resolved, and none were having issues only with partial music not showing up. All my artists show up, but it's only putting HALF the songs they have from each album into the player...