Hi Guy’s
I’ve been having the same problem and it does appear to be the EuconAdaptor in Nuendo.
I’ve been in touch with the Nuendo Support Team in the UK and this is the reply:
“Steinberg have realised that there is a problem/bug, so this has been fixed.
But there is one problem, this will not be fixed until Nuendo 6.5.30 has been released.
Hopefully this will be released soon, but this will cure the issue.”
So hopefully out next week then 
Regards
Ian