Symptoms:
You are configuring VXLAN network by HTML5 UI of NSX 6.4.1, NSX 6.4.2, or NSX 6.4.3.
VXLAN is configured on vSwitch that is not chosen in the "Configure VXLAN Networking" wizard.
Even if you unconfigure VXLAN and configure VXLAN again, the issue persists and VXLAN is configured on a wrong vSwitch.