DIAGNOSIS The wireless signal to the rear speakers is unstable. Obstructions or distance from the soundbar are the primary causes.
FIX Reposition the rear speaker transmitters. Ensure the transmitter boxes are elevated, not behind the TV or inside a media cabinet. They must have a clear line of sight to the rear speakers.
IF THAT DIDN'T WORK Check for interference. Move any routers, cordless phone bases, or large metal objects away from the transmitter boxes and the rear speakers. Power cycle the entire system.
HEADS UP The rear speakers are powered by the transmitter boxes, not the soundbar directly. Ensure the transmitter power adapters are firmly plugged in.