C#: Import Interface over Import Source Directory does not create Attributes

[berkic]

As a developer I like to import my c# Interface and modify get; set; and comments afterwards in EA, even better if it will be syncronized.
Currently I use the latest Version 15.2.1559 and my problem is, that I get only Operations and no Attributes. As far as I see, I can only modify Read Write, which is reflected to get and set of the C# interface, when a linked Attribute exists by pressing Property in Properties view.

If I do it afterwards manually, create a attribute and name the Operation the same as it still exist, it looks ok but if I press "Generate - Generate Selected Element(s)" nothing happens in the C# code. It sill have it get and set even if I selected only Read before. When I press "Syncronize" the attribute is gone and I am at the starting point.

What can I do here? Is there an other way (adapt some templates?)
Thanks for your help. Currently I have no idea how to use it.