Oh my...
The problem was I specified wrong Binding Path for a column in XAML, it couldn't find the attribute value, because such attribute field doesn't exist in specified service, that's the reason for my NullReference error...
So dumb mistake... :mad:
Sorry for bothering you and many thanks for your effort! 🙂
The problem with XML files is still up-to-date, but they aren't empty as i thought before - maybe it's a problem with my Excel?
Could you please check for me if the XML opens correctly into your Excel? (file attached)