Weird. Usually as a network device boots up it will broadcast and ARP packets including it's IP or request an IP from a DHCP server if it does not have an IP. I have used Wireshark many times to find the IP/MAC address of a network device where the IP was not known. So yeah maybe it is broken. Again Wireshark needs to be in promiscuous mode and the correct network adapter selected for capture. I can't remember if it is by default. Wireshark can also use filters to look for packets with only specific info.