I just had some trouble with a Rich-a-bri SET scene yesterday after loading SR5.  Don't know if it was related or coincidence, but it was the first time I encountered this phenomena.

I had a character sitting at a table. With AO on I would get lighter gray shadows where instead they should have been darker gray. Imagine a table leg with table and shadow. Then imagine turning AO on and the area close to the leg that would normally be darker suddenly showed up as a lighter ring. Same around Character shoes, etc.

I played around with Ray Tracing vs Depth mapping, but eventually just turned off the AO function for now until I figure out what is going on.