I am using Visio 2016 Professional edition.
I am not able to find an option to add operation and attribute to a class ( in UML Class diagram) .
After adding a class , when I double click on the class it provides a way to change the class name but don't find an option to add attributes and operations.
I followed https://www.experts-exchange.com/questions/25012074/Visio-2007-Can%27t-access-UML-diagram-properties.html
similar problem for Visio 2007 but I have all the settings as mentioned in this page still it didn't work.