Good spot. I see that problem too. Windows 7 with Firefox 14.0.1, though it acutally starts working again when they reach 7, not 6 instructables.

Here's are some members from Achievibles that have more than 3 and less than 6 Instructables:
m6233555m
arthurb
plane+phanatic
randomguy56
aeronut01
mkanoap
comodore

Here are some members that have 6:
z.backas
hack42moem
kcls

These have 7 and it starts working again:
aeray
chr
Derin