I have a few problems with iTunes Match, but my biggest relates to Playlists going missing.
1. Missing Playlists: I have a number of playlists which I've been carefully building for a very long time. A few are very large, with upwards of 1,000 songs. I signed up for iTunes Match, and a handful of the playlists (all of my favorites, which are some of the biggest) simply do not appear on my iDevice at all. For instance I have two Rainy Day mixes, one longer than the other. The shorter one appears, the longer one is just completely nonexistant on my phone.
2. Freezing Music App: I have two "Summer" playlists, both of which are quite long, in a folder called Summer. The folder appears on my iPhone... but when I tap it to play one of the playlists... the Music app freezes, and then eventually crashes, without ever opening the folder. Could this be because the phone knows there should be playlists there, but there are none and it doesn't know how to display an empty folder?
I want my big playlists back, they're what I listen to most!
Side note: Wow has my battery life been horrendous since turning on iTunes Match (I have an iPhone 4). This has never been a problem in the past for me, but suddenly it's dropping like crazy.
I have the same issue. I have some playlists on my phone that are blank which is really annoying. One of the Playlist is "Recently Added" for music that I added over the last week or so. The playlist shows up on my phone, but it's blank which is annoying. I can't access my newer music easily and I end up just pulling up Rhapsody or Pandora instead. Very frustrating.