Hello, Should anyone encounter this issue again, please confirm if you have {Engine}/Engine/Plugins/VisualStudioTools directory.
If so, please respond here, vote my comment, or confirm the plugin existence here RIDER-100275 Exception while generating include data for Target:UnrealEditor, Platform: Win64, Configuration: Development [System.ArgumentNullException: Value cannot be null. (Parameter ‘element’)]
Meantime, you either can try the workaround described above, or try removing the VisualStudioTools directory from Engine/Plugins to see if it solves the issue. Thank you!