Same problem here. Only just recently started doing it.
Where can we see the website in question?
Hi Takayuki,
Here is an example where I use the form:
https://waldbuero.com/event/waldbaden-zuerich/2021-04-11/
Thanks for looking into it.
Roland
What other plugins and theme do you use on the site?
Theme: Divi
The page I have shared is from The Event Calendar plugin
Then I also use
WP rocket
Yoast SEO
ShortPixel Image Optimizer
Pre* Party Resource Hints
Perfmatters
Try switching to the default theme, deactivating all plugins excluding Contact Form 7, and clearing all cache data.
Why you are advised to deactivate plugins and switch to the default theme.
@waldbuero It’s WP Rocket. I use WP Rocket on 10 sites. Disable caching on the page with contact form and it will work. Contact Form 7 also doesn’t play well with Autoptimize. Basically if combine Javascript, seems to break it.
Alternatively, you might just be able to just add /wp-content/plugins/contact-form-7/includes/js/index.js to Javascript exclusion list but may as well turn off caching on contact form 7 page anyways. Doing that will definitely work cause it did for me on 10 sites.
