Hi Saswata,
Thank you for the credentials, would you mind doing a testing for a plugin conflict. You can do this by deactivating all third party plugins, and seeing if the problem remains. If it’s fixed, you’ll know a plugin caused the problem, and you can narrow down which one by reactivating them one at a time.
I tried to do a plugin conflict test with the Health Check & Troubleshooting’s troubleshooting mode, but it can’t be helped as some of your plugins can’t be activated in troubleshooting mode. So you need to do an actual plugin conflict test.
Before you do that, please clear and deactivate first all your caching and optimizer plugins (Autoptimize, WP Super Cache, WP-Optimize).
Let us know how it goes,
Cheers!