I have a Launchkey Mini MK3, and when I plug it in my computer recognises it as what I assume to be a sound output device:
I try taking it out and plugging in again but Ableton won't recognise it at all.
However, if I remove the device and then try to plug it in, it works completely fine and Ableton can recognise it:
After removing device:
So it works fine, but it's just annoying that I have to open settings and go through this process every time I plug it in. (It will stop working as soon as I plug it in again)
Here's my MIDI port settings: