There's an issue with pyi files in VSCode, I have tried to get this working on 3 different machines with different extensions and all do the same. PyCharm/Eclipse on the other hand works as expected.
at ey.registerCommand (file:///c:/MyPrograms/Tools/VSCode/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:114:40314) at Object.registerCommand (file ...