When using the macOS driver for macOS Big Sur 11, Monterey 12, Ventura 13, Sonoma 14, or Sequoia 15, the USB indicator on the UM-ONE mk2 will only light up after launching an application such as MIDI Studio (Audio/MIDI Setup) or a MIDI application (DAW).
If the indicator still does not light up after launching the application, check the following:
- Check the COMP/TAB switch – Disconnect the UM-ONE mk2, move the switch left and right, then set it to COMP.
Note: Even if the switch is already set, move it to the left or right and then set it to "COMP" again. - Try a different USB port – Connect directly to your Mac without a hub, using another port if available.
- Confirm recognition – Open Audio MIDI Setup and check if the device appears in “MIDI Studio” or your DAW.
- Reinstall the driver – If the above steps do not resolve the issue, identify your macOS version and download the matching driver from the UM-ONE mk2 macOS Driver Download Page.