We did this, but it didn’t solve all problems.
Part of the solution was to copy the header.php from the enfold folder into the child theme folder. That solved the navigation problem.
The other problems seemed to be based on the wpml update we did at the same time. If we disable the wpml plugin the site stops reloading.

For now we are back at the old versions of enfold and wpml and will try the update again when we don’t expect many visitors on our site.