Hope I understood the problem correctly, how u are dropping the dll ? Each time u build the solution, u need to import to dlls to see them on Dynamo menu. (developer mode)
File > Import Library
Then u will see the category that matches the ‘namespace’ of your C# library.
U can start with a simple class library and create one static method returns string “hello world”, it really doesn’t need any of Dynamo dlls as reference to start with. or just clone to sample file https://github.com/hlp/ZeroTouchEssentials , build the solution and Import the dll in debug folder.
Let me know if u need more assistance