Yep, I’ve run into this before. Usually it happens when the WCF service reference files aren’t properly saved or included in the project.
A few things to check:
Make sure the generated files are there (like Reference.cs, .svcmap, etc.) inside the Service References/<YourService> folder, and that they’re actually included in the project (not just sitting in the folder).
Check your web.config. when you add a service reference, it writes endpoint configs there. If those are missing or didn’t get saved, the proxy won’t work next time you open the project. If it keeps happening, you can try using svcutil.exe to generate the proxy manually instead of relying on the “Add Service Reference” tool.