In the discovery.log, you may see there are messages with different machine names, e.g.
2020-07-02 14:36:03,180 [iscoveryActionExecuter|IPScan] [INFO ] Device 'rpawipv0001' is in scope: AU_XENDESKTOP_PROD_NAWWIPA0100
2020-07-02 14:36:03,227 [.DiscoveryTaskExecutor|PropertyDisco] [INFO ] Performing Xen Desktop discovery for device 'NAWWIPA0100'
In this case, there is possibly a DNS issue, please confirm the correct machine name and make sure that the hostname is being resolved correctly from the beacon (e.g. both the IP & computer name can be pinged)
The beacon discovers a Citrix Delivery Controller by interrogating WMI remotely on the target server. In order to test if this works manually, you can run the following in a PowerShell window on the beacon: