iCloud not syncing all files to Windows 10 PC

I use iCloud Drive to share files between my MacBook Air, my iPhone 11 Pro Max, and my original iPad Pro with no problems. When I add a file to a directory on any of my Apple devices, it pretty much shows up immediately on all of the other ones. I also have iCloud Drive on my Windows PC, and syncing is simply not working well.

Here's an example: I have a folder called Affinity Designer at the top level (iCloud Drive\Affinity Designer). It has four subdirectories under it. For simplicities sake, let's call them One, Two, Three, and Four. All four directories show up on all apple devices. On my PC however, only One and Three show up. One has only two files in it, and both are there on the PC. Three has four files in it, and they're all there too. But the subdirectories Two and Four never showed up at all. I have killed all iCloud processes using the task manager and restarted iCloud Drive, but nothing changes. If I click on the iCloud icon in the system tray, I can see the number of files to download grow and then diminish - but it never gets below 8 or 9 files. Those files don't seem to want to download, but I din't have any idea how to identify what they are. I also have some 30,000 photos in iCloud, so those 8 or nine files could be photos, I guess.

As I said, subdirectories Two and Four never appear on the PC. Two has 20 files in it; Four has 75. if I open the iCloud drive in a Chrome tab, I see all files in all four directories. As a workaround, I figured I could download the files with iCloud in Chrome, create the Two and Four subdirectories manually, and copy the files into those subdirectories. However, when I tried to create the subdirectories on my PC, they immediately got renamed Two 2 and Four 2. So it appeals the PC knows somehow that Two and Four exist, but it just isn't displaying them for some reason.

I tried another workaround: on my Mac, I made another directory named Affinity Designer SRB, and copied all four subdirectories into the new directory, Then I went and rebooted the PC - and this time, subdirectories One and Four showed up; Two and Three were nowhere to be seen. Four ended up with 58 of the 75 files in it - I downloaded the ones it missed, and now it has all 75 files (which tells me it's not a problem with an individual file in Four, at least.

I have checked to see that iCloud is up to date on my PC. Everything but iCloud is working fine, so it's not network related. The only thing I haven't tried is logging out of iCloud and back in - with 30,000 pictures, that's no small endeavor.

I'm running Windows 10 Build 1909 and up to date Apple operating systems.

Anybody have any ideas?