Fn+Start/Alt+F1 Opens macOS Display Settings Instead of IntelliJ Menu with Karabiner-Elements

[epifeny]

I'm experiencing an issue on macOS 15.1 when using IntelliJ IDEA with Karabiner-Elements version 15.3.0 enabled. I use a Logitech K850 PC keyboard (not the built-in MacBook keyboard), and the default shortcut Fn+Start/Alt+F1 is meant to open the "Select In" context menu within the IDE.

With Karabiner-Elements closed, the shortcut works as expected, opening the "Select In" context menu, which allows me to navigate to files and other contexts in IntelliJ IDEA. However, with Karabiner-Elements open, pressing Fn+Start/Alt+F1 opens the macOS "Displays" system settings window instead of the IDE's "Select In" menu.

Is there a reason this happens, and is there a way to prevent macOS from overriding this shortcut while Karabiner-Elements is running?

[
  {
    "type": "down",
    "name": {"key_code":"left_option"},
    "usagePage": "7 (0x0007)",
    "usage": "226 (0x00e2)",
    "misc": "flags left_option"
  },
  {
    "type": "down",
    "name": {"consumer_key_code":"display_brightness_decrement"},
    "usagePage": "12 (0x000c)",
    "usage": "112 (0x0070)",
    "misc": "flags left_option"
  },
  {
    "type": "up",
    "name": {"consumer_key_code":"display_brightness_decrement"},
    "usagePage": "12 (0x000c)",
    "usage": "112 (0x0070)",
    "misc": "flags left_option"
  },
  {
    "type": "up",
    "name": {"key_code":"left_option"},
    "usagePage": "7 (0x0007)",
    "usage": "226 (0x00e2)",
    "misc": ""
  },
  {
    "type": "down",
    "name": {"pointing_button":"button1"},
    "usagePage": "9 (0x0009)",
    "usage": "1 (0x0001)",
    "misc": ""
  },
  {
    "type": "up",
    "name": {"pointing_button":"button1"},
    "usagePage": "9 (0x0009)",
    "usage": "1 (0x0001)",
    "misc": ""
  }
]

[epifeny]

I see that when I turn this setting On, the IDE expected shortcut works.

.. but what am I missing out on when this is On as oppose to Off?

[epifeny]

I've also noticed that with this setting turned on, a fn + fX label appears next to each option in the Function Keys settings. My Logitech keyboard does have an Fn key, but pressing it along with the function keys (e.g., for brightness) no longer performs the expected actions, like adjusting the brightness.

[epifeny]

I also noticed that the Fn key on the MacBook keyboard works correctly, allowing me to change brightness and perform other functions. However, when I press the Fn key on my Logitech keyboard, Karabiner’s EventViewer doesn’t register it at all.