Actually, we need to fix this issue ASAP, so we troubleshot the website and compared it with the staging and development ones. We have installed an extra plugin called Stream (https://wordpress.org/plugins/stream/) only on the live website to track the actions of our logged-in users. This was the only difference between the development website and the live website. Also, we tracked the issue to see when it happened for the first time, and we found that the issue happened after installing the mentioned plugin, so as per the doubt, we deactivated the Stream plugin from the live website and checked the website for 4 days. We translated posts into other languages, and the featured images are fetching now. We are still checking the website to confirm the issue has been fully resolved by deactivating the plugin. After deactivating the mentioned plugin, we didn't face the featured image issue. We think this will fix this issue. We will also check the website for a week to confirm it is fully resolved, and we will mark this issue as resolved.
We have checked the issue for the last week to see whether it persists or not, and since the deactivation of that plugin, the issue no longer persists or has been found, and all the featured images are fetching and showing correctly now. I hope the issue is resolved now. The issue was due to the WP Stream plugin conflict.
Thank you for your understanding and your valuable support.
