Icon position in special styled buttons

The position of the icon in a special styled button is not correctly aligned within the button, e.g. not in the middle. Instead it is shifted to the top margin of the button. Please see the attached. How can we fix this?

For your convenience I am providing the button code here:
[button new_tab=”yes” special_style=”yes” border_radius=”2″ color=”pomegranate” title=”text…” link=”#” icon=”icon-external-link”]

Thank you.