Azure Monitor log: How to add parameters to a function

I want to create my first function in Logs (Azure Monitor)
The tutorial of Microsoft here is pretty simple:

But I have trouble with adding parameters to my own function. You can see in the tutorials screen how it should look like to store a function with paremters

But the parameters are missing for me if I want to save my own function.

I should mention that the scope I selected is targeting Application Insights (not classic, but using an analytics workspace). If I target something else I can create functions with parameters, but I need Application insights. Is that not supported?

Or... what am I doing wrong?