The Code Conversion Utility replaced a statically configured Call by Reference node with a placeholder node. This version of LabVIEW NXG does not support statically configured Call by Reference nodes. You cannot directly reference the subVI because it has a private scope.
Statically configured Call by Reference nodes are subVIs with a VI call configuration set to either Reload for each call or Load and retain on first call. The Code Conversion Utility replaces statically configured Call by Reference nodes with a subVI call, but in this case the subVI is part of another configured library with a private access scope. The private subVI is not accessible from outside its library, so the node was replaced with a placeholder node.
Replace the placeholder node with a subVI that has the same functionality. There may be a public equivalent to the private VI, or it may be necessary to reimplement the functionality of that VI. If you have access to the library containing the private scoped VI, consider changing its access scope to public.
If the previous suggestions don't restore the functionality of the affected code and the code isn't essential to the core functionality of your application, you can remove the portion of code. If the code is part of the core functionality of the application, you can use the VI Interop node to call your existing code, provided that the new code organization meets the architectural goals of your application. If neither solution meets the requirements of your application, do not migrate to LabVIEW NXG at this time.