Hi Leonie, do you see them in the model graph? Maybe the processes just do not contribute to results, even not with their supply chains, then you do not see them in the sankey diagram or contribution tree. You can check whether the processes are considered in the calculation if you check inventory results, total requirements, where all processes with their contributing factors are shown.
Side thought, if you have added the processes so that they are getting input from the reference process, as product, and do not add to other processes in the supply chain of the reference process, then they will not be considered in the calculation. But you probably did not do that?