If you are having issues with your Safari start-page icons not appearing, you may resolve the problem by deleting a single cookie from the device(s) that are not showing expected thumbnail icons:
Settings > Safari > Advanced > Website Data
Using the Search box, enter cdn-apple.com
The cookie should be found; swipe to the left to delete the cookie from your saved website data. After deleting the cookie, force-restart the device(s):
Force restart iPad (models with Face ID or with Touch ID in the top button)
If your iPad doesn’t have the Home button, do the following:
- Press and quickly release the volume button nearest to the top button.
- Press and quickly release the volume button farthest from the top button.
- Press and hold the top button.
- When the Apple logo appears, release the top button.

Force restart iPad (models with the Home button)
Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.

After restarting, be patient - as you may need to wait for a while for your icons fully re-populate the Safari start page.