With SDK 2.5 I add a new DockPane to my addin module, and put a listview on it with some listviewitems.
In the document outline I right click and choose add a copy ...

I remove the style from the middle item ...

I see it at design time ...

But not at run time ...

At runtime the visual tree for the middle listviewitem has no children ...

I see no mention of listviewitem in the style guide:
ProGuide Style Guide · Esri/arcgis-pro-sdk Wiki · GitHub
Am I doing something wrong?