I had issues with some metrics (including this one) when I first setup 7.11. Use WMI Explorer and connect to your VDA. Look at the WMI class 'ROOT\Citrix\Profiles\Metrics:LogonTimings'. You will have an instance for all current sessions and each session will have properties like 'DesktopReady', 'ProfileLoaded', etc. If this namespace doesn't exist altogether you have WMI issues that can be fixed with a few commands.
First of all thanks for your help I really appreciate it. I've checked WMI on a VDA with root explorer and it does show the info you are mentioning (see attachement).
Also almost every month after Windows Updates we do a fully scripted re-install of our VDAs and create a new PVS vdisk every single time. So we run a clean 7.12 VDA installed from scratch.
I do have to say we don't use Citrix UPM but a 3rd party solution for profiles however we use that since 7.6 and it always worked with that and we didn't disable any services that could cause the issue.
It's not a real deal breaker though, we really don't rely on logon data from Director for monitoring purposes but it would just be nice if it worked. It hurts my eyes to see it doesn't every time I open up Director