The issue has been fixed. Have made a code change in framework/functions/campaign-functions.php file at line number 361 from –
if (empty($form->ID) || $goal_option !== 'yes' || $target_amount == 0) {
to
if (empty($form->ID) || !in_array($goal_option, array('yes', 'enabled')) || $target_amount == 0) {
due to some data changes that happened in Give plugin 1.8 version. Will have the theme updated this week so that your change stays across updates. This way you won’t need to reapply the changes for future updates.
Thanks for reporting this.