So as of this morning, all of my local files were perfectly downloaded in my playlist on my phone. Somewhere between then and now, they have completely disappeared from the playlist. I added a few more local files in the playlist, but now none of them are to be found. I've restarted and re-logged in to my iPhone, didn't work. I also don't apply to some of the typical solutions. For example, I have enough storage on my phone; I am way under the 3,333 song limit; I am only synced on 2 devices. On my computer, the playlist has no issues. Also, on my phone, it shows the correct number of songs that should be in there, but when I actually go into the playlist, all of the local files are still missing. Any suggestions? This is incredibly frustrating. All help is much appreciated. 

EDIT: Problem solved. I was on a public wifi when I added the new local files. Now, on a private wifi, my local files have re-downloaded.