NodeModel error: Dereferencing a non pointer

So, i’ve been following the sample on this repository:

Speciffically the sample on the UISliderBound.cs class.
The error message i get is: Dereferencing a non pointer. I know that the most common cause for this error is that the function that the node executes is in the same assembly as the nodeModel Class.

But i can guarantee that this is not the case, and even though the function is in a separate assembly, i keep getting the same error.

Does anyone have any tip?

Thank you!

Edit: I’m using Revit 2020, and dynamo 2.3. The version of DynamoVisualProgramming.WpfUILibrary is

Any Tips? Thank you!