I would run a long extension cord from a different circuit in the house to the Master Bedroom. Then plug the both the sat receiver and AV receiver into the extension cord, both together and individually. This can help you determine if indeed perhaps some inductive pulse from the Master Bedroom AC line when the fan is controlled is causing the digital audio to drop and if so, which component is being affected.

Not sure what kind of fix would work best if the problem is isolated to the fan switch...

Maybe double check the fans wiring to make sure it is correct?

Maybe a higher quality fan or fan controller?