This issue is related to the scene explorer. There is a way to get it working in Slate and Compact material editor, and that way is to go back to the old-school Select by Name list view. To do this, all you have to do is go to: C:\Users\%username%\AppData\Local\Autodesk\3dsMax\2017 - 64bit\ENU\en-US\defaults\MAX and open CurrentDefaults.ini. From there, find the line that reads:SelectByNameUsesSceneExplorer=1and instead use:SelectByNameUsesSceneExplorer=0