In this week i had the same problem. I think tath a recent update of the plugin multistep has created this problem, infact some time ago all was right. I resolved it in this way: i’ve deleted the cache (images and JS) of the pluging WP FASTEST CACHE (Delete Cache and Minified CSS/JS) in ‘Delete Cache’ settings and also exclude the pages containing the shortcode for CF7 in ‘Exclude’ settings. Beyond this In case you use a CDN like CLOUDFARE purge the specific pages containing the shortcode for CF7.
Now all is ok.
I hope this is useful. The problem is the caching.
Sorry for my bad english.