My print cooling fan doesn't turn on during printing. It works fine when printer is idle and responds to power inputs, but never turns on during printing. I have checked the gcode and in superslicer it shows that during the first 4 layers the fan ramps up to 100%... but it never turns on during print. I notice though that no M106 S{} commands are issued in the gcode... so is the problem in the slicer? Has anyone seen something like this before?