Graphics.Blit to the screen not working?

I have a renderTexture with content (checked and working when applied as a texture to some geo) but when I Blit that rendertexture to the screen nothing happens.

    Camera.main.targetTexture = null;
    Graphics.Blit(R, null as RenderTexture);

Isn’t that supposed to just blit the texture to the screenbuffer?
Any idea why that’s not working?

Hello @AlexiJohansen123, I know this thread is old, but do you remember having found a solution for that ? I seem to have the same issue. Thank you !