Hi,
Unfortunately, there's no easy way to bypass the master intensity. You'd need to put back the master intensity to 100% and create multiple groups with their activation controlled via OSC and put the dimmer/intensity attributes in the proper group.
Alternatively, you may want to use the relative mode as a workaround to be able to control the brightness of some attributes independently of the master intensity. Create a new grid with the attributes you want to control independently (or use your existing grid if you want if all attributes are already there), select the attributes on the grid and enable the relative mode (the checkbox is in the right panel). The relative value is added after the master intensity has been applied.
I'll need to check whether this relative mode behaviour is a bug since the blackout button doesn't even work in this case. In your case, that's what you want but it might be confusing.