hard constraints will read Force, Angle, Torque and Distance
Glue constraints will read Strength and Impact
Sometimes you will glue things together and they will still seem to come apart (when attached to something animated for example). Try solving the RBD Packed Object on creation frame - this MIGHT fix it...
Check your Constraint Network's "Overwrite with SOP" field if constraints are not being deleted correctly. It should only be active (value of 1) for the first frame of the simulation. Then it should go back to 0. Otherwise, it will constantly read in the constraints from the SOP level (ie. replacing it with vanilla untouched constraints)
