In principle every MFD should see request product information, when any device informs itself on the bus. I have noticed that all devices does not do that. You could try to send product information in every 2 sec with command
NMEA2000.SendProductInformation to see does that make any difference. If it works it may still mean that there is something wrong, but we get a bit more information.
If you have real Actisense NGT-1, that is very strich and request information from all devices.