For more than five years, this has plagued all iTunes users for syncing music from the iTunes library on a desktop computer to iPod, iPhone, and iPad. Here are just a few posts from angry users regarding this.
Dec 5, 2012: https://discussions.apple.com/thread/4573038
Jan 5, 2013: https://discussions.apple.com/thread/4676111
Apr 15, 2017: https://discussions.apple.com/thread/7925928
Mar 26, 2018: https://discussions.apple.com/thread/8333944
I also have been running into this problem frequently because I have an MP3 music library on my desktop computer that I synchronize to my iPhone through a series of sequential and smart playlists in iTunes for Windows.
It’s already bad enough that the songs with the dotted circle are unplayable, because they are not yet downloaded to the iPhone, but the fact that iTunes displays the songs with dotted circles, knowing full well that they should be downloaded, but yet still refuses to download them, is really obnoxious.
These are the two ways I found to get these back onto my iPhone.
1. Delete the original song from iTunes music library, resync the iPhone, then add back in the song, then resync again. But guess what? The song will be removed from manually-created playlists. So, after adding the song back into the iTunes music library, I need to add the song back to playlists and then slide it back into place to reorder it.
2. From a suggestion from 7925928, locate the song on the iPhone associated with the gray circle in iTunes. Click it to play it. The song will be grayed out on the iPhone playlist. Then resync in iTunes. Again, this is a painstakingly long process, especially since you need to do a lot of searching in iTunes to locate the dotted circles, since there is no way to sort the dotted circle column to group them all together, and then on the iPhone for the song and then play it to make it turn gray.
Well, at this point, it looks like Apple is never going to fix this as they recently announced the end of iTunes. Many questions remain:
1. Will Apple Music still allow you to load and play and sync music files from a desktop computer?
2. Will a desktop version of Apple Music be available for Windows users?
3. Will Apple Music inherit the same synchronizing code from iTunes, which means we may haven’t seen the end of the dotted circles?