AO output just blurry noise when rendering large models

I have been using AO in Black & White mode / no shadows and find that on some models it renders perfectly, but on others with identical settings the output is strange–nearly all white, blurry, washed out, pretty much unrecognizable. This error seems to usually happen on larger models–anyone had this issue and (hopefully) know the solution?

Have you tried increasing the “Occlusion Distance” parameter?

Yes, tried adjusting that (as well as all other settings) but on certain models nothing seems to make a difference.

Also tried:

  1. Exploding everything in the model (in case there was some issue with a group/component).
  2. Copying/pasting all data into a new sketchup model.

See links below for some examples of working/desired output vs. error output
Hidden Line Export from Sketchup from working model
AO render of scene with desired result

Hidden Line Export from Sketchup from error model
AO render of scene with errant result

Hopefully this clarifies