Seems that wasn't fixed reliably. Still seeing lots of probe requests. Is there a https://support.apple.com/HT... talking about it?

Not aware of anything from Apple about this issue. It was just an assumption, sorry. What I did is test up to date devices (i think i even tested an up to date iOS 6) and couldn't get any specific SSID. The probe requests were still there, but SSID parameter was always set to Broadcast.

However I did see a lots of probe requests WITH a SSID parameter set but those were not coming from my devices :). I assumed they were not up to date.

I am very interested to know if the probe requests you're seeing are also coming from unknown devices: if they aren't, could you provide us with the iOS version you're using/testing with?

The devices I know are several iPhones 6/6+ running iOS 8.3.

Only possible when the wifi is in range.

So first you need to spoof the SSID ...

Loosely related: iOS devices are very talkative about seen Wi-Fi networks albeit Apple started to address such privacy issues with iOS 8, see http://www.reddit.com/r/Android/comments/2uyw50/wifi_privacy...

It doesn't seems to be iOS 8 only. Recent versions of iOS 7 seem to be fixed as well. (Tested my phone earlier this week)

How long did you test? I'd recommend sniffing for at least a few hours.