I ran into this UI bug the other day when I was trying to enable route redistribution on an Edge in a Secondary site of a cross-vCenter NSX deployment.
The Edge itself was deployed correctly, and configured to peer with a physical northbound router, however when I attempted to configure the route redistribution I was unable to do so.
Fortunately, the solution was simple - use the API.
Disclaimer! I am learning NSX-T, part of my learning is to deploy in my lab - if I contradict the official docs then go with the docs!
Lab Environment This NSX-T lab environment is built as a nested lab on my physical hosts. There are four physical ESXi hosts, onto which I will deploy three ESXi VMs, a vCenter Server Appliance, NSX Manager, an NSX Controller cluster, and two NSX Edge Nodes.