Calling WTSVirtualChannelOpen() lasts for about 10 seconds if channel (name) is not handled by RPD client plugin

Question

This is new to Windows 8. In former Windows Versions that call succeeded in either case (without delay), but a subsequent write failure indicated, that related channel was not handled by RDP client.

This kind of "Channel Probing" is a commonly used technique implemented within our products (and i guess other products do it the same way). But actually that new Windows 8 behavior causes our products to hang..

Is that experienced delay a bug (that may get fixed) or rather intentionally (a feature)?

Kind Regards, Andreas