Hey there,
I am really sorry for the delay of this reply as it is a weekend for us here.
Thanks for reported, it seems like Twitter already announced this last month
https://twittercommunity.com/t/action-required-sign-in-with-twitter-users-must-whitelist-callback-urls/105342 , now Twitter will forced all the app MUST be set that correct callback URL.
I've applied following callback URL into your Twitter app, it should work fine now, can you give it a check is it work fine now?
[gist type="php"]
https://yoursitedomain.com/dashboard/registration/oauthDialog/twitter
[/gist]
For those user site who hitting this following error when the user sign in via Twitter in Easysocial.
Whoa there!
The request token for this page is invalid. It may have already been used, or expired because it is too old. Please go back to the site or application that sent you here and try again; it was probably just a mistake.
You have to download my attached file and replace into this file location
JoomlaFolder/components/com_easysocial/easysocial.php .
Then access this following URL on browser.
[gist type="php"]
http://yoursitedomain.com/index.php?option=com_easysocial&twittercallback=1
[/gist]
Copy that callback URL and paste into your Twitter app callback URL section
http://take.ms/K6i4H