I think I finally found the solution (iPhone 6, iTunes 12.2.1.16).
When I used Cellular Data it seemed to work, not Wifi.
1) On your iPhone, go to "Settings" and turn on "Cellular Data".
2) Go back to "Settings" and scroll down to "iTunes & App Store" & turn on "Use Cellular Data".
3) Go back to "Settings" and scroll down to "Music" and turn off "iCloud Music Library". You should see "Genius" pop up above "iCloud Music Library". Notice when you go back to "Settings" and go back to "Music" it does not turn back on.
4) Plug your iPhone into your computer. Go to iTunes and click the iPhone icon in the top left corner. Go to "Summary" and under "Options" it now says "Manually manage music and videos". Check it.
5) Go to "Music" under "Summary" and check "Sync Music" and now you able to sync selected playlist like normal.