How to sync playlist created on iPhone to iTunes

Here is the Part of a solution as of iTunes 12.1.0.50.

1. Connect iPhone to computer via USB
2. If you have setup your iPhone outside of iTunes, then it is ok to click "Set up as new iPhone". This will not change anything in iTunes or your iPhone.
3. Before you click sync, you will want to make sure all the songs in your playlist are already downloaded to iTunes. You may be able to accomplish this by selecting only music to be synced. Beware that if you click sync your playlist will automatically be synced, but any music not already downloaded to iTunes will be deleted from your playlist on both your iPhone and in iTunes.

Unfortunately, after going through these steps there were songs missing in my iPhone playlist that were clearly listed in iTunes and on the iPhone playlist tab inside of iTunes. However, they were not present on my actual iPhone. Also, no new playlists would sync and when I tried changing the playlist from my iPhone and syncing it deleted all the missing songs from my iPhone and in iTunes as well. That meant I had to rebuild playlist again.

I tried exporting the full playlist from iTunes and importing under the iPhone tab, but all that did was duplicate that playlist in iTunes. This sounds a lot more like a sync bug as well as some unclear instructions for syncing.