After IPAM has a subnet whose CIDR contains -giaddr, and a pool, run this on the node:
lattice-dhcptest -server 127.0.0.1:67 -giaddr <gateway> -n 40
That fake relay address must sit in a subnet you created in the plan. Watch Leases and lattice_dhcp_allocations_total.
Empty trusted-relays drop relayed DHCP from other hosts; loopback still works.