I have a similar issue, but I think it's because after my old phone died (a Samsung Galaxy Note 4), I got a new Note 4 identical to the old one and just switched the SIM card out of the old phone and into the new one. Avast apparently realizes I have a new phone, because it says it last communicated with that phone over a month ago and it shows the IMEI of the old phone (which I suppose is the correct number), but the listing for the new phone simply says "N/A". The problem is, I'm afraid to remove the old phone from my device list for fear that my new phone will be considered lost or stolen and become inoperable. My phone is my life. I cannot afford to allow this to happen. Is this a legitimate concern? Is there some way to post the IMEI of my new phone to my Avast account?