I have an iPhone 4S (v5.1.1, jailbroken with Absinthe). I have been having lots of trouble with iTunes Match lately. Sometimes when I download a song, it will not play in the iPod player. I tap a song, and it plays the next file instead of the one I selected.
Using iFile, I verified that the file has actually downloaded to the filesystem (/var/mobile/Media/Purchases), and opened it from there using iFile's built-in audio player. It plays here, but there are gaps in the music (i.e. the first 2 seconds play, 30 seconds of silence, song resumes, 2 seconds of silence, resume, etc).
Has anyone else seen behavior like this? What could possibly be causing this? It happened on a fresh install of 5.1.1, before I jailbroke my phone, and has continued.