Forerunner 235 Offscreen Buffer Draw Bitmap doesn't show Yellow correctly

On FR235 I tried to make a new background which includes yellow. I used 0xFFAA00 as yellow and saved it as a 16 bit bitmap image 215x180.

function onLayout(dc) {
deallocateOffscreenBuffer();
// now's a great time to load the background image
resBackground = Ui.loadResource(Rez.Drawables.Background);
}

// update the watch face view
function onUpdate(dc) {

  // get local time
  var timeNow = Time.now();
  var localTimeInfo = Time.Gregorian.info(timeNow, Time.FORMAT_MEDIUM);
  clockTime = localTimeInfo;

  // set the day of week and day of month strings
  var dayOfWeekStr = localTimeInfo.day_of_week.substring(0,3).toUpper();
  var dayOfMonthStr = localTimeInfo.day.format("%02d");
  targetDc = dc;

  // clear the screen
  targetDc.setColor( Gfx.COLOR_TRANSPARENT, Gfx.COLOR_BLACK );
  targetDc.clear();

  // draw the background
  targetDc.drawBitmap(0,0,resBackground);

  // draw the 12 o'clock marker
  targetDc.setPenWidth(9);
  targetDc.setColor(cAccentColor, Gfx.COLOR_TRANSPARENT);
  targetDc.drawLine(DeviceOverride.TOP_HOUR_MARKER_LEFT_X,0,DeviceOverride.TOP_HOUR_MARKER_LEFT_X,DeviceOverride.TOP_HOUR_MARKER_HEIGHT);
  targetDc.drawLine(DeviceOverride.TOP_HOUR_MARKER_RIGHT_X,0,DeviceOverride.TOP_HOUR_MARKER_RIGHT_X,DeviceOverride.TOP_HOUR_MARKER_HEIGHT);

  // draw the larger hour marks
  targetDc.setColor(cAccentColor, Gfx.COLOR_TRANSPARENT);
  targetDc.setPenWidth(5);
  for (var i=0; i < 12; i++) {
    // skip the mark at the top of the hour and the three o'clock positions
    if (i == 9 || i == 0) {
      // 9 == top of hour, 0 == 3 o'clock
      continue;
    }
    targetDc.drawLine(DeviceOverride.HOUR_MARK_COORDS[i*4+0],DeviceOverride.HOUR_MARK_COORDS[i*4+1],DeviceOverride.HOUR_MARK_COORDS[i*4+2],DeviceOverride.HOUR_MARK_COORDS[i*4+3]);
  }

  // draw the date bar with day of week/month
  drawDateBar(targetDc, dayOfWeekStr, dayOfMonthStr);

  // if activity tracking is on, manually draw/update the steps and move indicators (if so configured)
  if ($.gDeviceSettings.activityTrackingOn) {
    if (cDisplayStepsIndicator) {
      var activityInfo = Toybox.ActivityMonitor.getInfo();
      var stepPercent = activityInfo.steps.toFloat()/activityInfo.stepGoal.toFloat();
      drawStepsIndicator(targetDc,stepPercent);
    }
    drawMoveWarning(targetDc);
  }
  // manually draw/update the battery indicator bars (if so configured)
  if (App.getApp().getBooleanProperty("DisplayBatteryIndicator",true)) {
    updateBatteryLevel(targetDc);
  }

  // draw the background and hands
  drawBackground(dc);
  drawHands(dc, middleX, middleY, clockTime);

  if (updateSeconds || ($.gPartialUpdatesAllowed && dcOffscreenBuffer != null)) {
    // draw the second hand, if configured
    drawHandCenter(dc, middleX, middleY, true);
    drawSecondHand(dc, middleX, middleY, clockTime);
  } else {
    // otherwise, just draw the center rings
    drawHandCenter(dc, middleX, middleY, false);
  }
}