The first question is how your site copied were created? If it was made by some kind of a plugin, then it seems like it doesn't link pattern properly.

If you copied sites manually, you must not forget about copying patterns as well and setting appropriate pattern IDs after that. Example of doing it programmatically you can find in this tutorial: https://rudrastyh.com/wordpress-multisite/sync-patterns-and-template-parts-across-sites.html

Maybe it can also be resolved the simple way:

1. Go to the all patterns page on your child site and check – do you have patterns copied correctly there?
2. If yes, just hover over the pattern edit URL and find out its new ID.
3. Do appropriate replacements in post content.

If there are not patterns copied to the child site, check the guide I provided the link above.