Having media layer defined causes toggles to 'stick' rather than be momentary in my experience

keyboard/ergodox_ez/keymaps/keymap_default.c

@@ -114,7 +114,7 @@ const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
  *                                 `--------------------'       `--------------------'
  */
 // MEDIA AND MOUSE
-[MDIA] = KEYMAP(
+KEYMAP(
        KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,
        KC_TRNS, KC_TRNS, KC_TRNS, KC_MS_U, KC_TRNS, KC_TRNS, KC_TRNS,
        KC_TRNS, KC_TRNS, KC_MS_L, KC_MS_D, KC_MS_R, KC_TRNS,