style="display: none; ....is put on a display template when the row is in edit mode BUT ALSO BEFORE THE GRID IS INITIALIZED. so it is normal that you find style="display: none; in the page sources. When the grid is initialized the style="display:
none; of each grid row is removed.
Another possibility is that you forget the Mvc Controls Toolkit js file...:)
@Html.DataGridFor(x => x.Networks, ItemContainerType.tr, null, "NetworkItemDisplay", null, null, itemCss: "normalRow", altItemCss: "alternateRow")
is working for me!! If you need to convince yourself (..sometime one want to be 1000% sure) delete the edit and add templates in the example that comes
with the binaries...and you will see that it works.