Components falling down during simulation


My question is about different reactions of conveyors during a simulation.

When i started a simulation where i used multiple conveyors and a shape feeder, one of the conveyor fell down, and the other stood still (it ‘floaded’). This can be seen in the two jpg.files that are added to this post.

Thus, my question is why the conveyors act different and how can it be changed? I would like to have the conveyors ‘fload’ like the right conveyor shown in VC_SIMULATION B.

Thank you.

Are you using Physics conveyors? Does the middle conveyor have lift offsets, which affect the height of its connectors/the yellow arrows used for PnP?