My unit has also been missing updates. It seems to me that it usually stops receiving when I am driving north ( antenna on the dash board and therefor no direct line to the satellite on the southern horizon) is it possible that this is the problem? Maybe someone that knows more about communications equipment could answer that.
where do you get one of those radar sets?, as far as some of the units working while others are haveing problems could have a thing or two to do with your vehicle choise, if your vehicle is say, latemodel and you have the Onboard Nav system, it could be that your Nav signal is blocking the updates, or if you have Satellite radio that could cause an issue, the antenna uses your cars body as a "Base Point" and uses 3 axices to create a 'Fix' on where your at in relation to the sat uplink signal, atleast it works like this in C.B and UHF radios, not 100% on Sat though, could be the same, or it could be something as simple as you need a bigger antenna
as i said before i wasnt sure if the two of them worked the same or not, i've only worked with Active antennas before, my GPS antenna i know at times will not work if i use my CB with my amp on,or if i'm sitting on the side of the road with my cellphone