Login with facebook not merging with existing user account

Technically not an AnsPress issue (that’s why asked it under general).

But Login with facebook through WP Social Login plugin doesn’t work (stuck at email already exist) if user is already registered. I tested on your this site too. Login with Google merged my details with existing account on your site. On the other hand, facebook stuck like screenshot.

Any way to work it around, in a way that it merges with existing account. I visited plugin developer’s support page, noticed similar issue asked many a times, but with no response 🙁