When I did my associations I didn’t do any hex conversions. I took the device ID directly from the link below and put that in the “node to write hex” field. That’s for the device you want to be controlled by the switch, not the switch itself.
I think if you leave the node end point at 0, it will use the next available node. So I left that at 0. I’d suggest picking “remove all nodes” in the group association type then press action button before trying again. That will clear associations you previously made.
Lastly, I was using an on/off switch so I used group 2. Per the following link, I think dimming is group 4, not 3 in your screenshot (Knowledge Base Redirect – Inovelli). But per that same link, it seems you may want to associate both group 2 and 4 one at a time. I haven’t associated dimmers before though so not sure.