I'm having the same issue with the same Nokia wireless qi charger - sometimes it works great, mostly not.
The N4 registers a connection with the audio tone, the white charger LED lights, the charging icon on the N4 shows it is taking a charge, but nothing (much) happens - maybe a slight charge but nothing significant. The battery usage screen shows the phone has been connected and has received a continuous charge.
The fix seems to be to reboot the phone. Then everything works as expected. But that defeats the purpose of having a wireless charger on my desk - I just want to be able to pick up the phone, use it and put it back without worrying if it is going to charge or not.
This is so frustrating. I charge my phone by USB at night so it's not a deal breaker but wondering if this is a recent issue (I have only had my N4 for 3 weeks).
EDIT: just confirmed I have a Rev 11 N4. So is this a known issue? Reason to RMA?