Datatable won't show columns

Thyrador

Hey there, it's me again. I'm still struggeling and don't know what's wrong with my configuration.
It won't even finish the debugger (it keeps stucking at "Uploading data to the server...").

The issue is, that it takes quite long to load the data and that it won't show any columns at all.
Anyone can see whats wrong here?

Or is it even possible to get the columns asynchronous via ajax, like with the result?

Here's the code after Razor processed the page: https://pastebin.com/yypBZHhs