While using the FLX S24 today, I noticed the following:
I have 16 generic dimmers on channels one to sixteen and 8 LED fixtures on channels 17 to 24. Everything seemed to be fine until with any of the LED fixtures fader up, the colour windows above each fader wheel came up, as expected, - Red, Green, Blue, White. However, when fading up any one of channels 1 to 16 the white colour option, inexplicably changed to red, and, in fact did control the red channel.
Going into settings and then attributes, the "always display intensity encoder" was set as "disabled". Changing this to "enabled" cured the problem with each window now displaying Intensity, R, G, B and white moved to the second set of colour options.