Everything you describe suggests that you may not have correctly unmapped your MIDI crossfader when you were deleting the mappings. If the "Enable external controller crossfader" option is unchecked, and the fader isn't MIDI mapped, then there's no way (other than autofading, or using the mouse) that the crossfader should move. The automatic mapping that occurs when you enable the option "Enable external controller crossfader" doesn't involve any MIDI at all - it related to communications between Serato DJ/Scratch Live and MixEmergency. This is why it's only working for your Pioneer DDJ-SX controller when using Serato DJ (it's not compatible with Scratch Live). It's also why it's not working when you go into MixEmergency control mode (as it doesn't receive communications from Serato DJ). Like I said in my first post - it's an issue mapping 14-bit controllers. They send 2 MIDI messages, one for the Coarse position of the fader (values 0-127, from left to right), and one for the Fine position of the fader (values 0-127, between every value of the Coarse position). This Fine position is what is being mapped, instead of the Coarse position. Changes in MixEmergency 2.6 have fixed this, which hopefully won't be too far away. In the meantime, when using the DDJ-SX, the easiest solution is just to make sure that nothing is mapped to the crossfader (when you enter MIDI mapping mode, the crossfader should be coloured red - no green at all), and use it with Serato DJ.
