Here is a fix provided by tambaqui on the github issues page:
“Hello, the quick solution that I have applied in my local installation is to add lodash as dependency:
In file advanced-backgrounds/classes/class-gutenberg.php, line 37, change:
$js_deps = array( 'wp-i18n', 'wp-element', 'wp-components', 'wp-block-editor', 'underscore', 'jquery', 'jarallax', 'jarallax-video' );
By:
$js_deps = array( 'wp-i18n', 'wp-element', 'wp-components', 'wp-block-editor', 'underscore', 'jquery', 'jarallax', 'jarallax-video', 'lodash' );
I hope they can fix it soon in the official plugin.”
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I tried this and it worked first on the edit page where the errors were gone, but then when I uploaded the changes to the actual page, I continued to find problems.
Later I saw that I could fix the remaining problems by reloading a couple of images.
A still unanswered question is why my other site with all the same settings, same host, etc. etc. runs AWB fine without lodash.