When setting up a DHCP scope on normal physical device, you usually have to specify the VLAN binding as well, I cannot see this option anywhere on the NSX Edge DHCP configurations. How do you configure that this VNI is supposed to get addresses from this scope?
If there are multiple DHCP Scopes on the NSX Edge VM, it understands from which DHCP Pool to give an IP from the gi addr parameter, which is the the IP address from which the Requests are coming from. (This address is used as the gateway for the DHCP Scope).This is the case when the Logical Switches are behind a DLR. If the Logical switches are directly connected to the Edge, then it understands from which interface the requests are coming from, as this interface would act as the defauld gateway for the Logical switch.
This link may help for detailed configuration: