I should apologize for being cranky. That does indeed work on my other PC, just not the one I use every day. However, the fact that this thread is still generating interest after the same solution has been posted many times, suggests that there are others
for whom it doesn't work. Let's see if we can figure out what's going on.
Total number of saved views: 5000
IDs of FolderTypes with custom templates:
{885A186E-A440-4ADA-812B-DB871B942259}
{7D49D726-3C21-4F05-99AA-FDC2C9474656}
{5C4F28B5-F869-4E84-8E60-F11DB97C5CC7}
You have templates created for Generic, Documents, and Downloads FolderTypes. I'm willing to bet what's screwing you up is that 5000. That's the max # of views that can be saved. When you hit that,
Windows has to delete a previously saved view every time it tries to save a new one. Have you noticed folders on the
Desktop not remembering their view settings?
The best thing to do is delete all saved views by deleting the registry keys:
HKCU:\Software\Classes\Local Settings\Software\Microsoft\Windows\Shell\Bags
and
HKCU:\Software\Classes\Local Settings\Software\Microsoft\Windows\Shell\BagMRU
Make sure all Explorer windows are closed before you delete the keys. Sign out & sign back in before launching
Explorer again.
You can export these for backup before deleting, but I wouldn't bother.
You will lose all saved folder views. The next time a folder is opened, it will use the views saved by
Apply to Folders if one exists. If not, it will use the machine-wide defaults found under:
HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\FolderTypes
But with the understanding that Apply to Folders works on a per-Foldertype basis, you can open each of the folders under This PC and set your preferred default view for each corresponding FolderType
(Desktop uses Generic), and then use Apply to Folders to create the template for that FolderType. And remember, the source for all this confusion & consternation:
Downloads now has its own FolderTYpe (even though it doesn't appear in the
Customize tab), it no longer uses Generic.

Another good thing about this "clean slate" approach is that your custom view will be used by the dialogs if created before the dialog is launched for the first time. So,
set all default view preferences for all FolderTypes in Explorer and use Apply to Folders before launching any dialogs!
I'm curious to know how the Downloads folder will open for you the first time. That will tell us if the Apply to Folders template was created correctly or whether views being maxed out interfered with its proper creation.
Keith