I'm attempting to model the Robotiq 2-finger adaptive gripper. Each finger is an underactuated 2-DOF, fivebar mechanism, but I'm modeling it with the underactuated joint pinned, which turns each finger into a 1-DOF fourbar. I'm currently trying to use an "connect" equality constraint to connect the outer joint of the finger to the fingertip (closing the kinematic loop), but once I do this, the mechanism is unable to move, even with all joints being unlimited (just to be safe). I also disabled collisions between all the geoms by setting their contype to 2 in case that was causing issues. This is a simple fourbar that is not at a toggle point, so I'm not sure what the issue could be. I looked in some of the downloadable resources for guidance, but didn't see any that included a kinematic loop. I've attached a minimal working example.