What happens if you tell it to display the group name on the first group?
If that works then I think you have found a bug. If you don't want to show the group name then try increasing the height of the first group.
there are known layout problems if the group widths are not exactly the same width all over - mostly it works but occasionally get confused. (but yes having titles on them all to ensure same height would also help.
@andhikasaja if you always want a fixed layout, so don't need the groups to flow below each other when you view it on a mobile device for example, then the best way is to have just one group filling the whole width and then you can position all the elements exactly where you want them on the dashboard.
