When the "Merge Properties" menu item is clicked, the data source isn't reloaded

[Merlin04]

When the "Merge Properties" menu item is clicked, the list of labels that will be printed does not reflect any changes made to the file since it was initially added. In addition, if the file is selected in the file picker again, it will still not reload. The only way to make it reload is to choose another file then choose the file you want to use.