Funkybunch - You mentioned thinking about going to BI, so I want to throw some observations out to you. I have a new camera where IVS doesn't work well so I figured this was a good time to check out BI, which has the potential to make the IVS not working a moot point. If you're seriously tempted, I suggest you try to reallocate or borrow a machine for a couple of weeks and run the BI demo version. It's not all that hard to load win 10 on a clean disk and put BI on top of it. After running the demo for a couple of weeks I decided to stick with the NVR for at least the short term. I have great fear of appearing to favor an NVR over BI on this forum. It's not that there's anything wrong with BI. It runs rather well, has a lot of nice features, and looks overall easier to use. It's just different, and what's important for me isn't necessarily important to somebody else. There were 3 main reasons I'm sticking with the NVR for now:
(1) With IVS and the NVR, the green box and red trip lines are shown in real time viewing and during playback. I sometimes track small animals and would often never locate what tripped the IVS without the green box and red line. IVS often picks up very low contrast objects that are close to impossible for me to see. If tracking just people or vehicles, this wouldn't be a factor. BI has a way to point out what trips its motion detection, but it's only during playback and requires extra steps.
(2) It looks to me like BI's motion detection capability has the potential to work just as well as tripwire and intrusion, but requires a lot more fiddling and tuning to get it there, compared to just drawing a line with IVS.
(3) Some of my cameras don't send out IVS events over the ONVIF interface, so I'd have to give up IVS with them. My problem, but may or may not be anybody else's problem too. You have to check out each of your cameras to find out.
I'm hoping you can get the NVR working the way you need it. You do need to be able to work directly with the cameras, so that part of the NVR needs to work for you.