I am using SharePoint 2013.
The problem is as follows:
There are two Site Collections in a single Web Application. With the following Paths: /sites/Site1/Subsite1/ & /sites/Site2/Subsite2
Using Export-SPWeb
"http://SiteCollection/sites/Site1/Subsite1" -Path "C:\Export.cmp"
I have Exported the Subsite1.Using Import-SPWeb
"http://SiteCollection/sites/Site1/Subsite2" -Path "C:\Export.cmp"
I have Imported the Subsite1 to Subsite2.
Everything is working perfect. The Subsite, the List, the Content Types, the columns all are getting imported. But except one, the Workflow instances that are created in Subsite1 are not getting imported in Subsite2.