I'm using C4D v11.5 on Windows v7 and I regularly use 'Ctrl-R' to render the current active view, which always worked as expected with IPP v1.9.5. However, since upgrading to v1.9.9n a few months ago (and now v1.9.9r) I'm sometimes unable to render the active view, either by clicking the menu bar icon, or using 'Ctrl-R'. When I try, there's a slight pause as though it were rendering, but nothing happens in the viewport. If I delete the IPP figure then hit 'Ctrl-R', it renders the scene in the active viewport as normal. However, if I paste the deleted figure back in to the scene, viewport rendering fails again. The odd thing is that the problem doesn't appear immediately. When working on a file in C4D I save frequently and increment the file number so that I have older back-ups. Sometimes everything works perfectly for a couple of hours, then the problem starts. Once it starts, I can never render to the viewport. I've tried loading the scene on a different computer (Win XP) and I have the same issue. However, if I load a previous version of the file which didn't have the problem, viewport rendering works fine.
I've noticed that if I copy everything from the C4D scene and paste it into a new file, 'Ctrl-R' works again, but it's only a matter of time before the problem returns.
Rendering to the Picture Viewer or to a file works as normal, but this isn't ideal as it slows down my work-flow.
Anyone else have this problem?