Actually componentsassembled with mechanism connections are not clearly identified in the Model Tree. They are in fact identified with a small icon that makes the user not adequately distinguish these components from the ones mounted with constraints (see fig. below)
Orange arrow: fixed component (ground body).
Blue arrow: components assembled with connections.
Green arrow: component rigidly constrained on a component assembled with connections.
Red arrow: component assembled with no constraints or connections at all (wrong "placement").
It would be nice if the user could clearly distinguish between packaged components and components assembled using regular mechanism connections (see an example below)