@eduiy16,
Thanks for the additional information. Do you use the free version of the plugin? Have you ever subscribed to 14-day trial of the Pro version?
Also, in order to understand what is going on with the language list, could you please follow the next steps:
1. Go to browser developer tools > Network tab while you are on the Settings page.
2. Click Save on the setting tab to initiate any action with the plugin.
3. Then filter requests by ssrv.cgi name.
4. Check the full information in Headers and in Response tabs for this request. Send us a screenshot.
5. Are there any errors in the Console tab? If any, please send us screenshot.
For your convenience, I’ve recorded a short video with the steps.
[video src="https://webspellchecker.com/app/uploads/2021/05/wp-plugin-troubleshooting-2021-05-14-12-47-11.mp4" /]
Regards,