Everyone's Latency is Unknown

[RolyB]

Prior to the latest update of the Windows 10 client I used to get latency ratings for other musicians.
Unfortunately everyone is now showing as "Unknown", even friends I have just been in a session with. It's as if my internet latency can no longer be calculated.
This makes it difficult to find suitable sessions to join.
Is anyone else experiencing this?
Any assistance would be appreciated.
Thanks
RolyB