Network Topology "Graph" tab always says "There are no networks, routers, or connected instances to display." This happens after a fix for bug 1661350 (commit f35eaa2d13fc5aff31b9a83dc729cc20b91fc611) was merged. Note that "Topology" tab works fine.
I couldn't reproduce this with the upstream master, neither in Chrome nor Firefox.
Created attachment 1420163 [details] network topology osp 13
python-django-horizon-13.0.1-0.20180323102049.el7ost.noarch
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHEA-2018:2086