Getting error Unable to decrypt string with openssl_decrypt() when uses clicks

The issue is resolved now.

To fix the issue we have updated Sendy to the latest version and updated your extension "Sendy for Joomla"

In addition to updating the "Sendy" and your extension "Sendy for Joomla" we found that previously the list id configured in Sendy - System pluign was numeric value and now we have replaced it with the list id which is shown on Sendy portal.