Unless I am missing an option Instance groups are saved on the server and are visible by everyone who can view those servers your choice is a grouped or ungrouped display you can't pick and choose what groups you see (that would also be a great feature request)
Problem is what group of servers is important to me may not be important to others and the second big problem is a server can only be in one group so if I want the xyz server in my group no one else can have it in a group for their app.
So I would like to see some personal group management where you can both create a group only you can see and also hide any groups you don't want to see