A lot of customers have either Niagara and FIN Stack running on the same machine or they have 2 instances of FIN Stack. Because of that they run into issues when they try to discover their Bacnet Devices - their results return nothing.
In order to find the devices in the network in the Discovery window the user needs to put the Bind Address in(this is represented by the local machine ip from where the discovery is tried - keep in mind the default bacnet port is 47809).
Here is an example: