Ok, maybe I’m missing something obvious here but here goes…
How do I render Ambient Occlusion in BPR that does NOT also inherit the directionality of at least on Light? For the life of me I cannot seem to get any AO unless I have at least one Sun type light active, and this always creates directional shading and what look like shadows from that light…even if Shadows are turned OFF globally. Using ZB4R6 here.
Hmmm. Might not be possible. AO is the shadows which need light to form?
http://docs.pixologic.com/reference-guide/render/bpr-ao/
That would kinda be a contradiction since it is called “Ambient” occlusion…not “direct” occlusion 
Ok, I went back to zb version 4.0 and it works as expected there. The change seems to have happened with 4R2, which is also when they got rid of the “color” swatch in the AO settings. In 4.0 you could use a Flat shader and get AO to appear on it, but no longer works in 4R2 and above. It’s as if AO and regular light shadows are somehow tied together. Not sure why they changed it but I’m not a fan of the current behavior.
Wouldn’t you want AO to be directional if you have at least one light source present? (in otherwords, no ao shadows where direct light is reaching).
For a more global look that’s based more on geometry than lights, you could try using the flat color material and masking by AO before rendering, or try taking another basic material and make it flatter by dropping the diffuse and specular to 0 while boosting the ambience value. This should work where the flat color doesn’t.
An alternative to Cryrid’s suggestion might be to use a LightCap. I’ve attached a quick example.
Thanks everyone for the replies. I’ve been testing some more in both 4.0 and 4R6 and from everything I can tell the AO does NOT work correctly in 4R2 and up! In 4.0 is worked perfectly and as per the universal description of an “Ambient” Occlusion pass, even on a Flat Shader. In the more recent updates there appears to be some kind of rendering optimization or ray sharing between lights and AO that was added which really makes getting a PURE AO render all but impossible. I’ve tried the lightcap file from Marcus but this does not even come close to the proper AO look that ZB4 achieved with a single button click.
The really frustrating part is that I keep getting very different results from render to render in 4R6. About half the time I get no AO at all, then if I slightly move the light (or maybe turn it on, render, then back off) the AO will suddenly appear again. I’ve attached some images that demonstrate what I’m talking about.
Here is another render from 4.0 using the flat color shader with AO on in BPR. Once again, just as you would expect.
