The QmitkMultiLabelSegmentationUtilitiesView currently provides five different widgets for the post-processing operations. The widgets for the operations Morphological Operations, Surface To Image and Image Masking also hold a tab, titled Labels.
This tab is supposed to include e.g. the QmitkLabelSetWidget but nothing is shown if the tab is selected. This is true for all three mentioned widgets.
It was already not working in MITK-v2018.04.2, so I guess it is not related to {D312}.