Display WP Posts widget breaks on Twenty Thirteen child theme

Firstly, thanks for this plugin and this widget. I updated JP recently and found that issues I had experienced with this widget have been fixed and it’s much appreciated.

I moved to a child theme on Twenty Thirteen, nothing changed but to create the child at first. Then my wp posts in the widget refused to load, displaying “We cannot load blog data at this time.” I applied a couple fixes from other threads, disabling cache and removing/re-adding the widget. I tried using a different wp website to populate posts, a site suggested on another thread.

I reverted to Twenty Thirteen from the child and the posts are populated again. I double-checked my child theme code, switched back to the child. Broken. Back to Twenty Thirteen proper. Fixed.

https://wordpress.org/plugins/jetpack/