This thread is resolved. Here is a description of the problem and solution.
Mixed content problem when changing from http to https
Follow the below two steps:
1) Gone to wp-config.php and changed
define( 'WP_CONTENT_URL', 'http://example.com/content' );
define( 'WP_CONTENT_URL', 'https://example.com/content' );
2) Deleted transient wpml_language_switcher_template_objects from *_options table.
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