After a few more hours of testing I can refine what I found for Dahua camera compatibility with BI, and actually think I have a final answer for my cameras that don't play well. For the older cameras:
1) When BI queries their capabilities, pullpoint is not on the list. Pullpoint, however, does work.
2) With onvif device manager, no events are seen if "use pullpoint if available" is selected. However, the events are seen if "use pullpoint only" is selected.
3) The cameras send event messages for motion detection, and BI picks them up correctly.
4) The cameras don't send messages for IVS events. The answer is that simple!
The newer cameras report pullpoint as a supported feature, work ok with "use pullpoint if available" in odm, and send messages for IVS events.
I also ran into the what I assume is a bug in BI that it keeps turning on motion detection in the cameras. There's an easy workaround for this, by just totally turning off the detection area in the camera. Doesn't matter then if motion detection is enabled or not.