This happens because the RadFormDecorator adds a padding to the controls that are loaded inside the RadToolTip which ultimately increases its height to more than the one specified in its markup. This leads to the table holding the contents to overlap the div that holds the callout and is therefore only visible in the case where the callout is on the bottom of the tooltip (i.e. the three Top positions).
What needs to be done in this case is to simply take the padding into account when providing the size for the RadToolTipManager - i.e. Height="227px" instead of 220 as it is now. The same can be said about the width, so it should also be increased to 467px.
This means that this is not a bug in the control, but rather a scenario we have not noticed (and therefore not taken into account) when creating the demo's layout. This update will be applied live with our next upload and as a token of gratitude for helping us discover it I have updated your Telerik points.
the Telerik team
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