I use Keyboard Maestro in junction with Ableton to switch presets/tracks during live sets. For some reason, with extended use, KM uses an ever-increasing amt of RAM, so I added a specific macro to quit and restart the engine (from the .zip of the first reply in this thread Is There a Way to Restart Keyboard Maestro With a Macro? ) that I'll often hit during my sets.
Whenever I do this, all my midi controllers disconnect for 5-15 seconds, then reconnect. Even testing with all macros disabled, and manually quitting and restarting KM, my controllers still disconnect as soon as I attempt to reopen KM. I'm wondering what's causing this problem, and if there's anything I can do to fix it. Thanks so much!
And with all your macros disabled, it will not be monitoring MIDI packets, so all it will do when launching is create the Keyboard Maestro MIDI port.
Beats me why that would affect your MIDI controllers.
You could try exporting your MIDI macros, and then deleting them entirely from Keyboard Maestro. Keyboard Maestro will not even create the MIDI port unless there are MIDI actions (enabled or disabled).
You should also check that there is nothing else going on, that no macros are firing when you quit or launch Keyboard Maestro, and no other software is doing anything when the Keyboard Maestro Engine quits or launches.