Delegate call in MATLAB .NET interface not working in MATLAB 2018b, worked till 2018a

I'm using the MATLAB .NET Interface to acquire data from a server application running in MS Windows. This application is using an assembly written in C#, this assembly provides delegates to inform the user if sth. happened during data acquisition. This delegate call (see code snippet with error message below) worked perfectly fine until MATLAB R2018a, but displays an error message when using R2018b or newer.

Code:

GDSAPIWrapper = Gtec.Gds.Client.API.Wrapper.GdsClientApiLibraryWrapper;

session_creator_died_delegate = Gtec.Gds.Client.API.Wrapper.GdsCallback(@obj.onSessionCreatorDied);

GDSAPIWrapper.SetSessionCreatorDiedCallback(obj.DeviceHandle,obj.session_creator_died_delegate,System.IntPtr.Zero);

Error message: Unable to resolve the name Gtec.Gds.Client.API.Wrapper.GdsCallback.

What am I missing?