I found this looking for the same answers. The responses do not answer the core question above. The workspaces only became active if I added/activated an R Terminal shell prior to executing any code.

From the image above, this doesn't seem to be an R terminal. It needs to say "R Interactive" where you have your current terminal label (which in your images says "Code >". That plus icon will reveal what terminal you can add. If you can't see R Interactive Terminal in the available list then I assume the R extension isn't configured correctly.

But appreciate this is old but still adding thoughts. I'm trying to get a similar feel in VS Code to RStudio - particularly configuring panels and so on.