When adding occurrences to an existing set from the search results, the widget hangs and does not confirm that the item(s) have been added.
If the user clicks add again a dialog opens informing them that the occurrences have already been added. However, searching on the set does not return these added items.
When viewing the sets through "My Sets" however, the added occurrences are included, so this appears to be an issue with the widget/set indexing? rather than sets themselves.