Windows Defender Antivirus Network Inspection Service issues since Windows 10 2004 update

So after cooling off a bit the other day, I went for the near-nuclear option and did a clean install of the OS moving to 2004 since the issue exists at 1909 which is where I was anyways. I think I would have to roll back a lot further to avoid it, and there were substantial security enhancements over the last 2 years :P 

Doing this cleared most of the problems I was seeing in Event Viewer. 

I had a brief scare with Defender Offline Scanner not wanting to launch but it eventually did -- not that it works anyways still with my internal harddrive configuration. This has been broken for 2 years now. But at least it is still broken in the same old way. 

The only "new" glitchy thing that I see is within Process Explorer, when running as Admin, there is a weird error text still under the path for Registry and Memory Isolation processes -- but I am beginning to think that is a 2004/process explorer issue. 

I can also successfully toggle core isolation on and off at will (at the expense of WdNisSvc running or not). This is likely because whatever other software conflict existed (xtuacpidriver.sys and iocbios2.sys) didn't get reinstalled because I did not reinstall ANY of the OEM bloatware.

So now the "only problem" is that even after the monthly update, Core Isolation and Defender real-time AV don't work at the same time as one another. 

As far as I can tell the issue still persists.

After updating to Platform 4.18.2008.4, alongside with KB 4566782, the error messages stopped, the Windows Defender Antivirus Network Inspection Service is up and running on my system. Core isolation is on.

I don't know where to find the update (tried searching microsoft web site).  I don't know if these are applicable to Windows 1903.  Should't these be updated automatically if they apply to my system?  The notes on KB4566782 seem to imply it was included in the August 11 update, which I do not have yet.  Is the Antimalware Client Version 4.18.2008.4 in that update?  If not, does it apply to my system, and if so, where exactly do I get it, and why was it not part of the "normal" update process?

Go into the Windows Search bar / Cortana and type Update, or however you navigate to Windows Update, and force a manual check for updates. It may take a little bit for your machine to be ready but that's how I did it. When I booted this morning, I had no updates when I opened it initially. Forced a check, and it found 3, a .Net update, the monthly rollup, and a defender antivirus definition file.

After updating to Platform 4.18.2008.4, alongside with KB 4566782, the error messages stopped, the Windows Defender Antivirus Network Inspection Service is up and running on my system. Core isolation is on.

I was very hopeful seeing your reply, thinking perhaps it might be fixed with the monthly rollup ... it was not. 

Enabling Core Isolation breaks WdNisSvc still :( for me at least.

If you have Core Isolation on, you should open Task Manager, go to Services and if sorting by Name, look for WdNisSvc; if sorting by Description, look for Microsoft Defender Antivirus Network Inspection Service. Make sure the service is Running and not Stopped. 

After installing the update and rebooting, I had Core Isolation off -- which makes sense. It was off. I toggled it on (because I did a clean reinstall 2 nights ago I was finally able to do this... ), and rebooted. I checked, and sure enough WdNisSvc was stopped. So I toggled Core Isolation back off and rebooted. WdNisSvc was running again. 

I would like them both on at the same time, please......

After updating to Platform 4.18.2008.4, alongside with KB 4566782, the error messages stopped, the Windows Defender Antivirus Network Inspection Service is up and running on my system. Core isolation is on.

I don't know where to find the update (tried searching microsoft web site).  I don't know if these are applicable to Windows 1903.  Should't these be updated automatically if they apply to my system?  The notes on KB4566782 seem to imply it was included in the August 11 update, which I do not have yet.  Is the Antimalware Client Version 4.18.2008.4 in that update?  If not, does it apply to my system, and if so, where exactly do I get it, and why was it not part of the "normal" update process?

I get the same with yours ...:) 

Just click "OK" and type "Windows Defender network inspection" in the search bar. Mine comes up quickly :)