This is just a note for anyone searching later who runs into this problem. When I worked it out I felt silly.
Boygrouping and TUIO protocol both use port 3333 by default. So configure one or the other to use a separate port or TUIOdecoder might get confused by boygrouping messages.
If you want to reconfigure the port in Community core vision 1.5 you will need to edit C:\Program Files (x86)\NUI Group\Community Core Vision\data\xml\app_settings.xml and look for an entry TUIOPORT_OUT.
Because it’s in program files you will need to edit with an admin privileges txt editor to save.
Also for best reliability make sure the UDP node feeding TUIODecoder is set to Discard and encoding set to ‘Windows-1252’
Background: (for future keyword searchers)
I was having an issue with Community Core Vision and TUIODecoder node when running vvvv as a boygroup server. No clients connected yet.
The issue was whenever I had any kind of renderer open in vvvv that CCV wouldn’t send TUIO unless it had window focus. I.E create a renderer and CCV appears to freeze. The issue then evolved into generally unreliable TUIO data.
The renderer thing turned out to be a red herring, it just seemed to slow down ccvs processing (presumably because it was waiting for drawing cycle to finish before sending TUIO data) that it would become the second message in the spread (behind the boygroup message which was first) and UDP node would discard it.