I attached a picture of the chandelier that we created and are trying to control via X10.
WOW! I want me one 'o them things!
But your attic must be a rats nest of wires.
Your description of getting stuck during a dim, reminds me of a time I used hacked X10 modules (sans internal chokes) to dim video studio lighting. They would get stuck also. I had a similar phenomenon when dimming strings of Christmas lights laying in puddles of water.
First, looking at the other responses it is probably software related, so go down that road first. My thoughts are hardware based as the hardware was causing my episodes of getting stuck during a DIM from a wired "Maxi" controller.
Here is a couple of questions:
When they are being dimmed and "get stuck" does it always seem to be about at the same brightness level?
Does this getting stuck or not responding to a Dim command happen to both WS12 circuits, or only one?
When "stuck" will they respond to an "OFF" or an "ALL OFF" command?
If they will not respond an OFF command I suspect a noise problem generated by at least one bulb on each circuit.
What makes an incandescent bulb make noise? A poor connection in the socket resulting in arcing. Look for any of your bulbs flickering. OR (sorry for this) make sure each bulb is tight in socket.
Good luck