This issue occurs in Dynamo 0.8.1 for Revit 2015.
- User makes a selection in a node with a drop-down menu (e.g. "Element Types" or "Categories")
- User clicks the drop-down menu to browse other options.
- User subsequently decides they want to maintain the current selection, so they click off-node somewhere on the canvas so as not to edit the current selection
- Despite not having selected a new item from the drop-down list, selection will revert to to the first available item in the list
- Data is altered in the graph in an undesirable manner