Why won't Itunes Match sync all songs to my iPhone?

It would seem there is a communication issue between iTunes Match and your iOS device. Glad to hear the other portions seem to be working out okay. I had this same issue as I'm still using iTunes Match as I ponder the Apple Music. The songs I have pitch def and own are most important. U u is point and iTunes Match is handling that just fine. I advise turning off iCloud Music Library and then signing out of your account on the devise. Then power off the device for a few minutes. Turn it back on and enable your WiFi or LTE connection then immediately sign into tour account using your Apple ID. Then enable iCloud Music Library in the settings under music. Keep in mind that iCloud Music library is the new term referring to any cloud enabled on your device, that's whether it's Apple Music or iTunes Match.

A quick side came to mind that maybe you need to enable "show all music" which is now called "offline listening". This is located in the music app under My Music where you would change views for Album, Artists, etc. It's a drop down menu at the top of the page. If you scroll to the bottom you will see a toggle switch for Offline Listening. This must be turned off to see all your available music in iCloud.