Suddenly can't sync playlists on iPhone 5, iOS 6.1.4

[Cairo-Blue]

I was downloading several playlists at once—perhaps that's the problem. In any case, I've followed Spotify's suggestions: plug in the charger, turn off auto-lock...  I don't think I'm anywhere near the 3,000-plus song limit. I've stopped trying to download several playlists at the same time. Now I'm trying to sync each playlist one playlist at a time. Sometimes when I turn on "Available Online" for a particular playlist, an white exclamation point within an orange circle appears next to each song where the download arrow normally appears. What does this mean? Just now, I closed out the Spotify app, then turned it on again. I tried synching one playlist that had had those explamation points—being careful to turn off "Available Offline" for any other playlists. Now the download arrows are white (in the gray circles), but nothing's synching! Help!

[Peter__]

Hey! Welcome to the community 🙂 

How much free storage space do you have on your iPhone? 

Spotify won't start to sync unless you have 500MB+ of available free space. 

Peter

[Cairo-Blue]

Good to know! I had more than enough space, but when I opened the Spotify app, I discovered that all my synched playlist had "Available Offline" turned on! So I started turning each off, and the playlists I had started synching the other night--and which had started synching--began to sync again! But what do those exclamation marks mean?