It works okay for me.
Drums: 58.1 (About what I expected since I am pretty poor at drumming.)
Bass: 92.6 (I play guitar and bass quite frequently, exclusively on expert. Not surprised this was a little higher.)
Guitar: 91.3 (See above)
Solo vox: 87.7 (Some stuff is just out of my range, I guess?)
Keyboard: 80.9 (WAY higher than I thought, though I suppose my few times playing keys on guitar might have dragged the average up.)
Pro keyboard: 45.9 (Barely started at this, so that's fair enough.)
97.2 on drums, 95.5 on bass, 93.3 on guitar, 93.7 on vocals, 93 on harmonies, 96.9 on keys, 94.8 on pro drums... I guess that's good? I haven't been even remotely close to good at Rock Band in over a year so I don't know. Every other instrument is around 50 or 40 because I don't play them that much.
Only 81.1 on drums, but it is for 1339 songs so there must be some pretty difficult ones in there...
I think the dashboard stopped updating on my side, it says 140 GS on pro keys, I have 154, and 10 GS on pro bass, I have 14.
Mine too :_(
Weird, if it only affected Blitz and the store well I haven'T tried using any of those XD