If I remember correctly the 'Show related records' used to work fine in the Attribute Table widget, but it seems to have stopped working recently.
I select a record in the parent layer, I click on the 'Options' button to get the drop down menu, then click on the 'Show related records' option. When I click on that option, the Attribute Table changes focus to the last displayed table, but the related records are not shown. In fact, the table doesn't show any records, it just shows up blank. The only way to get the table to display the records is by using the layer widget and re-opening the attribute table.
Anybody else experiencing this?