Tiling grouped taskbar items - flawed?

On my recently installed new XP Pro PC, say I have a group of files or
folders in my taskbar (as a result of using the option 'Group similar
taskbar buttons' in Taskbar Properties). When I r-click and select
Tile Vertically, or Cascade, I do not get the correct result, namely
seeing all the images, files or folders, neatly arranged. Instead, one
or more is missing. It seems that it's hidden behind whatever was the
last window with focus, before the group operation. The only way I can
get the proper behaviour (e.g, see 3 images tiled or cascaded) is if I
first use 'Minimize Group'.

Do others get same behaviour please?

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Terry, East Grinstead, UK