Symptoms:
When you are configuring an interface on the NSX Edge with the Primary and Secondary IP, the routing table is taking a next-hop through the lowest IP address configured on the interface as a connected route.
For example:
1a) If you configure an Edge interface having a Primary IP as 172.25.255.20 and secondary IP as 172.25.255.21. Here, IP 172.25.255.20 (primary) is the lower IP address.
1b) Check the routing table on the Edge, it shows the next hop through 172.25.255.20.
2a) Now after changing the IP address where the Primary IP is 172.25.255.20 and the secondary IP 172.25.255.12. Here, IP 172.25.255.12 is the lower IP address.
2b) Check the routing table on the Edge, it show the next hop through 172.25.255.12 although it is a secondary IP address on the interface.