IP address has been removed because endpoints in NTA 4.0 are grouped by hostname, so showing single IP address would not be precise. For example, let have a computer with hostname laptop01, running over office and getting new IP from DHCP every 2 hours. In past NTA would show multiple single endpoints based in changing IP address. NTA 4.0 will display single record for laptop01 summing all data transferred under its various IP addresses. For that reason we cannot show single IP address next to laptop01 record.
Anyway we are open for ideas, so if there would be enough demand for getting IP addresses back, there might way to re-appear them in one of future NTA versions. Feel free to create a poll in feature request section.
Definitely include the most convenient way for you how to deal with the multiple IPs problem (e.g. show latest one, show expandable list, have option to switch grouping by IPs, etc.)