Solo current track keyboard shortcut doesn't work

I’m wondering if anyone has any ideas on where I should start digging to figure out why pressing ⌘@ to solo the current track suddenly stopped working. Re-assigning the keys in settings also doesn’t work; pressing ⌘@ does absolutely nothing. ⇧⌘@ or any other variation of modifier keys combined with ⌘@ works just fine (except ⌥⌘@, which also seems to be eaten by the OS), it’s just ⌘@ alone that doesn’t work. I’ve looked through System Preferences in OS X (10.6.8) to see if there’s any other app subscribing to the shortcut, but there isn’t. It’s only “Open In Mellel” (god knows what that is) under “Services” that even have ⌘@ defined, but it’s unchecked and off, so it doesn’t apply.

I’ve tried rebooting my MacBook Pro and restarting Renoise, quitting other applications (like Alfred), without success. Any ideas?

Edit: Suddenly it started working again. Seemingly nothing has changed. Weird.