There are a number of people using Cooper switches with ST in the following thread, you might ask there to see if they’re just using the generic Zwave dimmer device type or something else:
I have some Cooper Aspire Z-wave dimmer switches (RF-9540 master switches and RF-9542 auxiliary switches). I got the Aeon Minimote to associate the auxiliary switches with the master switches, and that worked fine. Now both the auxiliary and the master switches will turn the same light on and off or dim it up and down.
Also, the auxiliary will update the master’s state correctly. If I turn the light off with the auxiliary, the master switch shows as off. If I dim the light with the auxiliary, the master’s level changes to match
Problems arise with the master switch updating the auxiliary’s on/off state and dim levels. If I turn the light off with the master, the auxiliary still shows its state as on, and I have to physically push the auxiliary button twice to get it back in sync. Same th…