Jeff, which filter is the 'F10'?
For a couple of years, I had been moving breakers to keep the X10 devices on the same leg of the 220. Finally decided to use the .1 & 18uh series network across the legs. When I did that, some distant devices on the 'original leg' quit working. However, the devices I had installed on the 'new' leg did, indeed, begin working. I then determined that a camera power supply on the breaker with the new devices was shunting the signal. Not enough to shunt the signal to the new devices, but enough to shunt the signal to the distant devices on the 'original' leg.
Thus far, it seems that only one device in the entire house significantly shunts the 120 kHz signal. Does that seem odd? I have a house full of electronic and electrical stuff.