Blazor looses reference to InteractiveServer

If I use the default blazor template setting the interactive mode to Server on project creation, then when I press F5 all works.

I dont like the folder layout of :

Components/Pages

I want to move the Pages folder to the same level as components, so that I can use the Components Folder for my own components and thus keep the structure more meaningful.

When I move my Pages folder and all pages up a level suddenly :

@page "/counter"@rendermode InteractiveServer

the InteractiveServer redlines in VS. I've been searching for ages but cannot figure out why it is doing this. Any help greatly appreciated.