[Avalonia] Beginner attempting a spreadsheet application. Having issues displaying rows.

I'm really hoping that someone with some experience may have some time to assist me. This is my first time creating a UI of any kind as well as utilizing the MVVM development pattern, so I'm very out of my element. I am having issues with displaying rows of a DataGrid. If you are available, please reach out with a time/place and my desperate self will be there! Thank you!