QMK Alt-Tab macro

keymap.c

#define ALT_TAB     M(KC_ALT_TAB)  // Macro for Alt-Tab
enum macro_keycodes {
  KC_ALT_TAB
};


const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
    [0] = LAYOUT(
        KC_MUTE, KC_ESC,  KC_MPLY, \
        MO(1),   KC_UP,   ALT_TAB, \
        KC_LEFT, KC_DOWN, KC_RGHT \
    ),
    [1] = LAYOUT(
        RESET,   BL_STEP, KC_STOP, \
        _______, KC_PGUP, BL_STEP, \
        KC_HOME, KC_PGDN, KC_END \
    ),
};

const macro_t *action_get_macro(keyrecord_t *record, uint8_t id, uint8_t opt) {
    if (!eeconfig_is_enabled()) {
        eeconfig_init();
    }

    switch (id) {
        case KC_ALT_TAB:
            return (record->event.pressed ? MACRO( D(LALT), D(TAB), END ) : MACRO( U(TAB), END ));
    }
    return MACRO_NONE;
}

I think the macro keycode should be offset (not start at 0):

KC_ALT_TAB = SAFE_RANGE