Precomputed visibility breaks due to cached component transform error

Development Rendering
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1

I’m working on a mobile project with mostly static (non-movable) objects. When Precomputed Visibility is working, my frame rate is consistently 30-35FPS and above on my Android test devices, and 45-60 on iOS. Without Precomputed Visibility, I get 15-20FPS.

Most of the objects in my scene are Blueprints with one or more StaticMeshComponents attached. When I need to rotate/scale instances of these objects, I do so on the StaticMeshComponent rather than the parent object, as there are other components that are affected by the parent object’s rotation.

Occasionally, when I load the map, I get a bunch of warnings like the following for each of the objects on which I have manually rotated/scaled their StaticMeshComponents:

LogStaticMesh:Warning: Cached component instance data transform did not match!  Discarding cached lighting data which will cause lighting to be unbuilt.
/Game/Maps/MyMap.MyMap:PersistentLevel.BP_Photo_Wall_C_3.Photo
Current X=-190.000000 Y=1.000000 Z=194.000000 Cached X=-190.000000 Y=1.000000 Z=194.000000

Note that the “Current” and “Cached” transform values are actually identical, so I’m not sure what it’s even complaining about.

If I deploy to device when these errors are present, stat initviews tells me that only a fraction of the meshes are being statically occluded, and the framerate suffers dramatically. If I delete the Intermediate and Saved folders, rebuild lighting, then deploy again, static occlusion works brilliantly and I get a good framerate.

I’m at a point in my project where I’m regularly doing Production Quality light builds and cooking content for iOS/Android. I only have a 13" Macbook Pro (no dedicated GPU) available to perform my iOS builds. Cooking textures on this machine takes literally a full day, so deleting my caches and rebuilding lighting is a massive hassle.

2

I should add that simply rebuilding lighting doesn’t fix this error; there’s something in the Intermediate or Saved directories that needs to be deleted first, otherwise the error still shows up after a light build.

I realise that I don’t need to delete the entire Intermediate and Saved folders, but I’m not sure exactly which files are causing the mismatch. Much of the time spent cooking the game on my Macbook is compressing asset textures, so I’m definitely doing myself a disservice deleting these every time.

3

Actually, rebuilding precomputed visibility immediately prior to packaging seems to do the trick, but it is annoying that this has to be done every time.