I was getting an error to remove the "mark of the web" from a .resx file and so I opened PowerShell as administrator, navigated to the folder in question, and issued an Unblock-File -Path myfile.resx command. I've also done it using the full path.
Now I am trying to bring the form into the project using Add Existing, but the .resx file is not being imported. However, for another form, when I choose Add Existing and click on the form's .cs file, Visual Studio (2019) brings all three files into the project in one fell swoop, its.cs, itsdesigner.cs and its.resx; but on the other form, the .resx file is not imported. In fact, Visual Studio does not even display myfile.resx in the list of files when I choose Add Existing.
What has Unblock-File done that would make the file invisible within Visual Studio?