How to stack items in item hangar?

the used functions

Sanderling.MouseDragAndDrop(oreHoldItem, OreHangarsStack, MouseButtonIdEnum.Left);

and the way over

ClickMenuEntryOnMenuRoot(IUIElement MenuRoot, string MenuEntryRegexPattern)

both seams not to work. Is there a bug with mouse input?

I have seen a context menu entry labeled “Stack All” in the inventory. Using this context menu entry did the stacking for me.
See the screenshot below for an example of the context menu: