Contact sensors 2nd Gen show weak signal at times

I just install the Ring Alarm system. The Alarm base is centrally located and not more than 30 feet from all sensors. At times when I arm the system, one of the sensors shows weak signal but not all the time. If I leave the system armed, the sensor that shows the weak signal clears and another sensor shows a weak signal. If I disarm and then rearm the system all the sensors clear. This happens randomly and not with the same sensor. All batteries on all show fully charged.