Nope. None at all - and we spend 95% of our lives in surround.
What I would do at this point (are you on Mac or PC) is completely trash prefs & rebuild them.
Firstly, take a backup just in case and on a PC it goes something like this:
Go to Users//AppData/Roaming/Steinberg and copy the folders for Nuendo 5, 5.5 and Nuendo 6 into a “BACKUPS” folder in the same location.
Then delete the contents of all the files from within these folders. You may even be okay to delete the whole folder (I never tried so don’t know for sure) but get rid of the entire contents of them all.
Now launch Nuendo 6 again, and it will start afresh with a brand-new set of preferences. It will need setting up again, and you will need to be sure any plugin paths you need for VST2 plugins are correctly pointed in the Plugin Information window under Devices.
Then reinitialize the other versions in descending order, so no version can ever “collect” possibly corrupted prefs from an earlier version by mistake. This is most likely the cause of the problem - a corrupted prefs file somewhere.
If you do not want to trash all the prefs, just open each folder & delete the following:
Defaults.xml (will force a VST3 rescan)
VST2xPluginfo.XML (for Nuendo 5.x)
VSTpluginfo v2.XML (for Nuendo 6.x)
VST2xPlugins Nuendo.XML
VST2Blacklist.XML
VST2Blacklist Nuendo.XML
This will force a rescan of all plugins & require VST2 plugin paths to be reset but will leave ther bulk of your prefs alone