Songs won't transfer to ipad

Hey there. I'm trying to transfer a playlist full of songs from my computer via iTunes to my iPad. It's something I've done many times before, but lately it hasn't been working. I have the latest update on my iPad & running Yosemite 10.10.5 and most updated iTunes. I have 29 GB available on the ipad. iPad model # is MD512LL/A - don't know if that helps or not...

So, basically, I drag the playlist file onto my ipad in the menu sidebar in iTunes and it will only load in 2 of the 12 songs. Always the same two songs, which are in the middle of the playlist. The others just sit there with the little dotted circle next to them, hinting that they will get loaded next, but no matter how long I wait, they never load. All songs are "checked", though I don't think that matters usually when transferring songs. What's going on here? Anyone know how to fix this?