Do you see tracks that suddenly stop? This may be a good exercise to determine the cause.
Here you see a bunch of tracks recorded by my receiver. At lower, right, there are a bunch of tracks that suddenly stop. That can’t be a coincidence. My house is near the highest local elevation, but in that direction the elevation is slightly higher. My house is 2 storeys tall, and the antenna I’m currently using is just barely above the peak of my roof. So let’s overlay a line in that same direction over a map of my neighbors’ houses.
Yeah, right along the edge of that house. The house must be blocking the messages. It seems clear that when I elevate my antenna, this issue should clear up. That house is a single storey house, and according to this site, It’s only about 5 or 6 feet higher than my house. Given that the house is shorter, I thought my feeder could see over it, but I guess not. Elevating the antenna will help with that. I’ll be doing that later.