Please deactivate all the third party plugins, activate parent theme then clear cache and check back.
If the problem continues then leave all the third party plugins deactivated and provide admin panel login details of the website with the permission to debug then we will troubleshoot with the theme plugins.
I have logged into your website and all the third-party plugins are still activated.
Please deactivate all the third-party plugins activate the parent theme and then tell me with the permission to debug then we will troubleshoot with the theme plugins.