This worked for me.
Ok, the thread is 1,5 years old, but the problem is the same for me. My experience is, that it can´t, in my opinien, be caused by settings outside the max-file. I have some scenes where all works fine and others, where I have the same problem as described above. Who has the time to uninstall and reinstall the software when stucking in a project? So I opened two sessions of MAX side by side , one with a scene with working VFB and one with a scene with the error. Then I compared step by step all the settings in the render setup window. Yes, ALL the settings. All pull down menus in expert mode if available. No succes- even if all settings are the same for both scenes. The same I did with the environment window and I tried if with sunlight or domelight and with differen types of cameras. Only one time I thought I found a fix. After I hit “Rendering-->Rendered frame Window” it stops showing the progress in the VFB, which worked fine. But only one time. I have also the same experience, that the “Rendered Frame Window” of MAX is always working fine, even when the not working VFB is open beside it. Sometimes I had the experience, that a new scene works fin and after some time of working with it teh error occurs. I will search a little more, but I someone have a solution which is not published here - please do it now!