Wrong position for CustomPoint and ReferenceLine with datetime on the x-axis

In the project attached, add a new reference line or a custom point via the context menu of the plot in the project explorer. A new line/point should be created having the position, i.e. datetime, corresponding to the middle of the x-range. Instead, the value 1970-01-01 01:00:00.000 is shown in the properties explorer.

When creating via the content menu on the plot in the worksheet, the line should be placed at the position under the cursor. In this case we show the proper value in the project explorer, but the line is drawn at the wrong position initially: datetime_positioning.lml