Use a new feature added to LabWindows™ /CVI 2019 and later to use NI Type information, as this option fixes the compiler error.
- Build >> Target Settings >> Type Information >> select Add NI Type Information resource to DLL
Figure 1. Type Information Window
- Disable Add type Library resource to DLL
Adding Type information should provide better integration with TestStand 2019 and later to be able to auto-populate function names and parameters when calling the LabWindows™ /CVI DLL.