ARIS Architect: Assignment icon unavailable

The first level assignment works properly. The assignment icon takes us to the corresponding organizational unit in this example model, as seen below:

When clicking the assignment icons, we can easily go to the next organizational unit. The problem is that the assignment icon is no longer available after clicking the first level of assignment. 

Note that all assignments have been done; I've been checking our models and compare them against the United Motors Group DB (example database for ARIS) and they look quite similar. However, the assignment icon is still unavailable.

Note that the assignment icon is totally missing. So at this point, we would like to figure out how to make the assignment icons available for the next levels after.

Thank you very much for the assistance

Regards