I tried deploying the flow to Production org using Change Set and the flow was modified in my Sandbox Org. After deployment, Salesforce created 2 versions of the flow in Production org and one was blank. When I searched in google, I found out that this is one of the known issue. Here are the details and you can subscribe to this link, if this issue affects you so that you will be notified by Salesforce when the issue is resolved. Thanks!