Why do I have a ton of missing file (exclamation point) icons in iTunes, when the songs aren't actually missing?

I noticed lots of songs in my desktop iTunes and Apple Music weren't displaying in the iOS Remote App. I realized each song that Remote isn't showing also has the exclamation point icon next to the song track number. But these songs aren't really missing. When I click the song in iTunes for Mac, the song plays just fine and the exclamation point goes away. I guess I could do this for the thousands of songs that have this issue. But I'd rather click a "Find All Missing Songs" or "Reconnect Library" option, or something like that. Help?