When you click to edit VLAN1 for an edge, there is no context menu that appears.
Additionally, you observe the following error messages when you check the Java developer console when you click on VLAN1.
This is due to defect #138964 which is fixed on 6.0.0.0, 6.1.0.0 and planned to be fixed on future builds for 6.2.
Please open a support case if you need assistance with a workaround for this behavior, and past the link to the article on the case description.