What types of changes are you trying to IPR render?
From the following website:
"Any change to an attribute that affects the visibility calculation, whether it is a topological change like adding or removing a surface, or a geometric change like moving CVs on a surface, requires another IPR render before you can see the effect of that change. Attributes that affect visibility are:
- Any transformation applied to any object or camera (since moving an object or the camera may change what is visible at each pixel).
- The resolution of a depth map produced for a light (you must regenerate the depth map before you can see the result in IPR).
Also note that if you add or remove geometry to or from the scene or if you change the UV mapping values for a texture, you will need to perform a another IPR render before you see the change in IPR. Examples of these kinds of change include:
- When you select a new group of faces on a polygon surface, even if the surface is already in the scene. In IPR, selecting a new group of faces to texture is equivalent to creating a new surface.
- Turning Fix Texture Warp on/off changes how the UV mapping values are generated in an IPR render. This situation is analogous to modifying polygon UVs by changing their placement.
Finally, if you make changes to shadow maps, image planes or background color, you must manually update the IPR tuning region (select IPR > Update Shadow Maps or IPR > Update Image Planes/Background)."
"Terminat Bora Diem, Terminal Auctor opus."