Why are my SQL Perfmon counters returning Zero?

I have set up a Perfmon data collector set on one of our servers with SQL server running on it. I also have a scheduled task which imports this data into SQL (set up by following this open source project: https://github.com/heraflux/BLGtoSQL ). All this runs with one user on the local machine. After leaving this running for a couple of weeks I have created a report to look at the data gathered so far. All the Perfmon counters EXCEPT the SQL ones work. All the SQL counters return zero - even though I know at least some of these counters CAN'T always be zero (e.g. User Connections, Free Memory KB etc). What's odd is that when I run and import the exact same setup on our development server the SQL counters work as desired. I've checked and the user has the same local permissions on each server. I've also granted the user with the following permissions on the SQL server: Connect Any Database, Connect SQL, View Server State. When looking at the SQL counters live on Perfmon I've found that they also don't seem to be working. I'm pretty stumped as to why they aren't showing anything.