I put v562 on my Nexus 5, replacing v557 after clearing 4.2.12 cache and storage, then force stop and uninstall.
v562 is not showing WiFi graph bars on the N5, whereas I'm sure that 557 was.
I just checked on my Nexus 7, which still has v557 installed, no graph bars there either. (I don't think that I checked the N7 yesterday after installing 4.2.12_557, it just worked on the 2.4GHz channel that I already set on the Spark using the N5 which also had v557)
I'm doing some experiments, like reboots, to see whether the WiFi graph bars are intermittent or not.
If I can't get them to appear, I'll re-install 4.2.12_557 on the N5 and see whether they're there.
Sorry for the complicated post fellas.
Screenshot from Nexus 5 with latest 4.2.12_562 installed - no WiFi graph bars (note that I'm on CH11 as shown on the channel index: