From Conveyor error

Hi,
i want to transport an assembled product from a conveyor to a buffer but there occurs the following error: “Transport output error: The status of the product within its process sequence is lost.”
Do you know how to solve this?

hi,

missing steps in process flow editor?

unfortunately not:
image

that would be a common mistake, perhaps without making further assumptions, you share the layout

The product which is partly assembled is being transported by a conveyor from 1 to 2. From there its transported from 2 to 3 (interpolating transport). At process 3 the final assembly steps are made. Then it is being transported back to 2 (interpolating transport) and from there by the conveyor to 4. From 4 the product is supposed to be transported (interpolating transport) to a buffer (5). But at 4 the product stops on the conveyor and the error occurs.
I tested to transport the final assembled product directly from 3 to 5 by interpolating transport. Surprisingly this works.