Smarthome devices used "preset Dim" and standard "Dim" commands.
X10 brand, Leviton, and other manufacturers conform to a "newer" X10 standard that uses "extended code Direct Dim" and standard "Dim" commands.
I don't have a WM100 but if it is sending extended code Direct Dim commands. Maybe the 2466DW and other Insteon dimmers with an X10 address maybe getting confused. Or if the 2466DW is sending a Preset Dim back to the WM100 when the local controls dim it. It maybe getting confused.
Here is a test 2876DB Icon Dimmer with a C1 address in it. 1132CU interface with Smarthome Manager Essentials software.
Since they are two way. Local paddle changes are sent back on the power lines.
On and Off send an X10 On or Off. Dim with the paddle and the X10 command of a Preset Dim is sent.
R: C1 - 3:56:12 PM 9/24/2018
R: COn - 3:56:12 PM 9/24/2018
R: C1 - 3:56:18 PM 9/24/2018
R: COff - 3:56:18 PM 9/24/2018
R: C1 - 3:56:22 PM 9/24/2018
R: 35% Preset Dim 3:56:22 PM 9/24/2018
Status request when at a dim level is a On and then a Preset Dim level.
T: C1 - 3:56:41 PM 9/24/2018
T: CStatus Request - 3:56:43 PM 9/24/2018
R: C1 - 3:56:44 PM 9/24/2018
R: CStatus=On - 3:56:44 PM 9/24/2018
R: C1 - 3:56:45 PM 9/24/2018
R: 35% Preset Dim 3:56:45 PM 9/24/2018