Safari Not Generating Webpageicons.db-shm or Webpageicons.db-wal files

Following an upgrade from Lion 10.7.5 to El Capitan 10.11 with a clean install several months ago, I encountered the typical challenges many face with disappearing web icons from Bookmark lists — all replaced by the infamous blue dot icon. The easy solution was to always keep an updated copy of the Webpageicons.db file in a backup folder on my desktop, so if I had to empty the Safari cache and/or Clear History (what amounts to a Safari Reset), resulting in the loss of all Safari Webpage Icons, I could just quit Safari, then replace the Webpageicons.db file in my ~/Library/Safari folder with a copy (automatically updated daily) stored in a folder on my desktop. The process also required deleting the Webpageicons.db-shm and Webpageicons.db-wal files from ~/Library/Safari.Both files are automatically re-created every time Safari opens if the old versions have been deleted.

This process has worked perfectly dozens of times for more than a year... until today.

Because of some problems viewing video this morning with the Safari browser, I Cleared the Cache, Cleared History, quit Safari, replaced the Webpageicons.db file in my ~/Library/Safari folder with copy (updated yesterday), deleted the Webpageicons.db-shm and Webpageicons.db-wal files from the ~/Library/Safari folderand then restarted Safari. But instead of seeing my usual Bookmark list with webpage icons intact, I was confronted with the blue dot web icons everywhere.

Thinking I'd perhaps made a mistake, I repeated the procedure, but this time there were no Webpageicons.db-shm and Webpageicons.db-wal files present in the ~/Library/Safari folder to delete. I surfed a few websites from my Bookmarks list which I know generate web icons and sure enough, their web icons appeared on my Bookmarks list, but all the other web icons remained blue dots.

I can see that the Webpageicons.db file is good because it is 48mb in size. I even reloaded the last Webpageicons.db file that I knew was still working from a recent backup from a few days ago. So the data is there in the Webpageicons.db file. It's just not being displayed. The obvious problem appears to be that Safari is not generating Webpageicons.db-shm and Webpageicons.db-wal files in the ~/Library/Safari folder when none are present.

Oddly enough, I still have several web icons present on my reading list in the sidebar.

Anyone have any ideas?