I noticed that my answer here Why do programmers write closed source applications and then make them free? did not give me a Good Answer badge. I noticed this after I suddenly received a Nice Answer badge for it, a few weeks after it passed 70 upvotes. This sounds like a bug to me, unless there are rules that are specific to community wiki answers that I'm unaware of?
Bear in mind that badges are never removed.
If you previously got a badge for a deleted or migrated question, you won't get the "next" one of that type.
The total count of badges of that type is how this is determined. Go ahead and count up the totals of answers with >= (n) votes on your user page.
I don't know if this is your answer or not but I have noticed that some things like badges and reputation and acceptance percentages, etc don't always update or appear right away. Maybe its still on its way?
I made a feature request question so that we could get some indication on the badges as to when each badge will be awarded on meta so. Still hopeful. It might be useful to also know if you knew if any of your badges have lapsed due to migration or deletion.
Some badges are awarded instantly, some at the end of the day (I guess after a batch run or sql job) and some (like tenacious) 7-10 days after you qualify for them.
I think that Good Answer falls into the 'will be awarded at the end of the day' bracket - so after this much time I guess its not going to come.