2. Please increase MaxInputVars to 5000 or 10000, currently its value on the server is 1000. You may need to contact your website hosting company to change this for you or change it from your server control panel. hidden link
3. Also I can see that you are using older version of WPML Multilingual CMS and WPML String Translation plugins. Please update ALL WPML plugins to it latest official release. Or you can download it from your account: https://wpml.org/account/downloads/
4. If still issue persists, then please try to check it by deactivating all third-party plugins (except Toolset) and switching back to the Default Theme (e.g. Twenty Seventeen theme) to see for any possible conflicts with any of the plugins or themes?