Styling/triggers breaks DataGrid styling

[LukazTrisauskas]

I'm still learning WPF, while trying out MahApps. I was trying to add a style/trigger to show status message while async method is running and data is being loaded. I found a few solutions on StackOverflow, but each time I tried them, they break the DataGrid styling.

For example - https://stackoverflow.com/a/4704513

How could I do something similar without breaking the MahApps styling?