Yeah, I've tried on all three. Full should acquire from .3m to infinity so that's the obvious one, but the others give the same results.
Just tried it outside in good light, with my daughter about 8 feet away from me, f/4 in manual and nothing (it gets close, but no solid light). Put the lens in MF mode and it's fine.
A colleague at work has a 7D he can try it on, so I'll take it tomorrow and we'll see. I've also fired off a mail to Canon in case they're aware of anything (can't believe the internet wouldn't have picked something up though). It's brand spanking from Amazon, so a swap won't be a problem.