There are two possible reasons the save campaign button is grayed out in your campaign:
Reason 1: User permissions
You are a User with no or limited permissions to edit the campaign. User permissions are set by the admin or account owner. In case the Campaigns permissions are set to “view only (cannot create or edit)”, the save button will be grayed out. In the same manner, the delete button is grayed out when the no delete permission is given:
Reason 2: Empty email node
You've created a campaign, and added an email action item to your campaign, but don't have any emails in the email bank. You then clicked the save button to dismiss the window:
If this happens, you need to delete the empty email item, create an email within the email bank and add a new email action item with selected node.
If you're still having troubles with your campaigns, please take a look at this article or go to our live customer support.