Last couple of times I've been on Vassal has been for playtesting so we've been locking the room.

Then words like "invite" or "accept invite" which none of these features are becoming apparent or obvious to me.

So do I need an update?

My Vassal auto updated a few weeks ago, so its possible. check your version against the vassal site.

I have been playing Vassal games this week and haven't had to download any new updates or anything.