Thanks for the reply. In my case it seems to happen only while gaming. I've been playing Frostpunk, so I'm not sure whether it happens in other games as well. I've never noticed it before.
Also, it seems to happen only after a while, when the system gets quite hot.
The problem with the led persists after I exit the game, but as soon as I open iCue and select the current profile again, everything goes back to normal.
I'll try to turn of the SDK and see if it makes any difference.
Edit: just for info, I've been using LL120 fans with a Commander Pro + Lighting Node for months without any issues and I haven't changed anything. So, it's definitely not a problem of set up or wrong configuration.