Songs with Exclamation Point on iPhone but not in iTunes

Hi,

I've faced the dreaded exclamation point issue before in the past and I can usually skirt around it by pointing iTunes to the correct iTunes Media Library folder in Windows Explorer. Or sometimes by deauthorizing/re-authorizing my current computer.

Currently, I have a somewhat different issue. When viewing the contents of my iPhone 6, under the "On The Device" header in "Music" most of my songs have the exclamation point by them. When I find a few examples of these songs in my main iTunes library, however, there is no exclamation point and the songs play fine.

I think I have already tried syncing. I have tried dragging and dropping some of these exclamation point songs onto the phone. Nothing is working so far. Any ideas?

Thanks!