Odd behavior of "Calculate Field Values" in Layout Mode.
Normally, when you right-click a field name and choose "Calculate Fiekld Values", only the selected rows are affected. If you do this in View > Layout mode. the values in all rows are replaced.
Selection Layers Wiped on Change of Symbology
If a new layer is created by right-clicking a layer and choosing "Create Layer form Selected Features" you can successfully change the symbology of the selected features by clicking the legend patch in the table of contents.
If you try to change the symbology of the selection by going to layer properties > symbology > choose symbol for all features, the layer loses its selection and all features that were in the original layer are returned.