No, these are truly plug n play when done correctly. While it's slightly more confusing when they threw Activation and other security measures in the mix in 2015, it's still fairly simple. Don't return it just yet, this is a simple issue with what should be a simple solution. Let's run through a few things.
In Order:
1) Your 3.3.4 looks green and leafy. All current generation Hikvision firmware is red and black/dark gray to match their general branding and color scheme. I have no idea whose idea it was to make their NVRs look like a forest. Cute, but I don't see the professionalism or UI cleanliness in that. On any older NVRs I've brought up to 3.3.4, it has always been red. The leafy theme ended around 3.1.3 in my case. That was for the 7700s and yours is a 7600, so that might vary slightly.
Bring the NVR up to the latest firmware, 3.4.1. You appear to have an E2 revision of the 7600 series NVR. These also appear to be generic versions of US Hikvision equipment, so firmware upgrades are safe from any region locking disasters. Fetch here:
NVR_EXX_BL_ML_STD_V3.4.1_151225.zip
Download, Unzip, and either:
A) copy the firmware (digicap.dav) to a flash drive and upgrade it from the maintenance menu right on the NVR
B) Sign into the web interface of the NVR over your network, and upgrade it from the maintenance menu on there using the same firmware file as described in (A)
When the NVR reboots, deforestation will have already occurred (leaves be gone) and everything should be red now. The NVR shouldn't need its settings reset, but I'll leave that as a last resort option.
2) Camera firmware is not an issue at this point, so we'll leave that alone for now. I do need to know what they're running at the very least. Ditch iVMS for any of the troubleshooting, it's a little clunky. Instead, use SADP. SADP will scope out anything Hikvision present on your network, no matter where or how it's hiding. Fetch here:
SADP_v3.0.0.2build20150911.zip
Connect your computer directly to the NVR PoE switch. (if you're using all 8 cams, kill one for testing purposes). Turn off any other NICs (WiFi for example) and open SADP. you should see your NVR, and then all of the cameras you have connected via that PoE Switch. Please post a screenshot of this, and I can help you try and figure out why the NVR can't see them. The default IP on the cams is usually 192.x.x.64 (I've seen varied default IPs recently, but this same pattern matches them all). This doesn't seem to be a problem with the NVR, but moreso the cameras. Perhaps they didn't clear out all the way. When in doubt, there is what's called the 30/30/30 reset, which is overkill for these, but basically you plug in the camera, hold reset for 30, unplug, keep holding for 30, plug back in, hold for 30, and it's a guaranteed reset. However this procedure is ultimately only intended for Broadcom chipsets. Hikvision uses Ambarella.
3) On the NVR, make sure all 8 are set to PnP. Looks like you've already figured that much out. You cameras appear to be on the 10.0.0.x network. Depending on how they were setup in iVMS, that might be part of you problem. However you've now set them to PnP, so there should not be any issues now, aside from ensuring the cameras reset to default. Post that screenshot and I'll see what might be wrong. If they truly reset, and the NVR didn't reconfigure them to PnP (you would have a picture of some sort), all of the cameras should have the same default IP. Additionally, selecting a camera should ask you to input an admin password for the first time. (This is the activation feature at heart). Do not enter a password, that's what the NVR's job is. Doing so will negate the PnP functionality, as it locks down the camera and doesn't allow the NVR to freely connect to it to "Activate" and auto config everything.