Windows Defender bug

A recent update for Windows Defender introduced a strange new bug that causes it to create lots (sometimes millions) of junk files which eat space on the C: drive and can bring a PC to a crawl.

To resolve this, we're supposed to look for a new Windows Defender update using Windows Update. The update is to v1.1.18100.6 which fixes the bug so it won't create any more junk files.

The next step has to be done manually after that update is installed because it doesn't get rid of the junk files it already created. We're supposed to navigate to: C:\ProgramData\Microsoft\Windows Defender\Scans\History\Store

Then with the files visible in that folder, press CTRL + A to select all files. Then press SHIFT + Del to permanently delete the files from the C: drive.

But...

1. Does anyone know where to find the version number for Windows Defender that's installed? I can't find it on my Win 10 PC and there's no recent entry for WD in the Windows Update History or in Windows Reliability Monitor. All I see are virus definition update version numbers. I manually ran WU but it didn't offer any new WD updates, aside from the latest virus definitions file.
   
   
2. I navigated as far as the \Scans folder, but Windows won't let me open it. So I can't get to the \History\Store subfolder to delete any junk files that may be there. Using the Everything search tool, I can find that last folder, but when I double-click it in the search results, it still won't open.

What am I missing...? 

You can read more about the bug here.