I previously posted about my adventures upgrading my music library to the iTunes Plus versions. These are DRM-free and have a higher bit rate than the usual iTunes fare. But there is also something hinky going on with iTunes Plus.
For some reason, iTunes Plus does not always recognize that I have multiple songs from the same album eligible to be upgraded. I had previously purchased three songs by Julia Darling from the album The Living Room - Live in NYC - Vol.2 . Sometime after my initial purchase, this album was made available in an iTunes Plus version, however, I was allowed to upgrade only one track of the three I had purchased. The other two remain undetected by the iTunes Plus upgrade mechanism or algorithm or whatever it is that powers it. There are other songs in my library in the same situation.
Get a fix on it, Apple!