Favorites icons in Safari showing as grey blocks

iPad Mini5, 64gb, 18.4.1. Today on the Favorites screen, as seen in the screenshot below, all the icons are showing as grey blocks with a letter or number inside, instead of as regular color icons appropriate to the site. Same with the Suggestions. At one point, maybe half of the icons came back as usual, but later it was back to full grey. I tried powering down a couple of times. Any ideas what might be causing this and how to fix it?