Comment 1 for bug 1981923

If the Invert option is not working this is unrelated to the TM8.
Could you please share the xml snippet of the mapped pitch slider?

FYI: for high-res pitch sliders you can use the 'script.midiPitch' helper
https://github.com/mixxxdj/mixxx/wiki/midi%20scripting#helper-functions
On my TM4 this I use this (note the '-' to invert):
engine.setValue(group,"rate",-script.midiPitch(control, value, status));