Configuration that is using a layout similar to the following is not allowing discovery to take place correctly:
PHUB > PROXY HUB (via IP #1) = PROXY HUB (via IP #2) < NAT IP HUB via tunnel
Release : 20.3
Component : UIMHUB
This type of configuration requires that there would be a tunnel between the PHUB to PROXY HUB (via IP #1) as well as a tunnel between the PROXY HUB (via IP #2) and the NAT IP HUB.