Unraid Docker Containers Custom Network IP Not Showing in Leases

[InioneCan]

I have multiple Docker containers in Unraid using the custom network type so that they have their own IP address. I can access them at their IP addresses, but I do not see them under leases in DHCP?  This is preventing me from accessing via their hostnames (e.g. plex.local:32400)

Anyone able to help me figure out why/how to get their hostnames working or have them show up in DHCP leases?