Render Region in Vray not working

I am used to rendering a region of an image by rt clicking the render button and it just rendered the region I selected. Vray renders the whole image in the selected box. Now I have to open vray frame buffer and select the region render button at the top. Much slower process. I am using VRay next. Anyone else see this?

That is a known problem.
When you show the VFB window, without rendering first, it does not initialize an actual renderer. It only shows a window. If you frame a region at this moment, it will be lost. The region itself is not kept in the VFB - what you see in the VFB it is just an UI element. The actual region data is kept in the renderer’s data structures. Obviously one must exist in order to keep the numbers somewhere. Once a renderer is initialized, the problem does not occur.