In Visual Studio, attach to the process w3wp.exe
You may need to run Visual Studio as administrator.
Once attached to the process, navigate to your customized screen on the Sage 300c web UI.
In Visual Studio, open ensure the symbols are loaded for the controller dll.
Use your custom screen, and any breakpoints you’ve set should be hit.
Make sure the pdb and the dll are matching versions, or VS will refuse to load symbols.