I am able to migrate *.xgm files using a post migration step one at a time. However, the post migration step seems to behave inconsistently if I tried to execute post migration step for 2 or more objects.
Adding a semi-colon at the end of the post migration command and then execute the command again.
When you select three objects and click interpret, it evaluates the command three times and puts the objects/host name/user/password etc in the command and you end up with THREE commands on the right hand side. However, how would this be parsed by SQLPLUS or another command line interpreter as one line? So, try adding a semicolon to the end of the command on the left side of the window. Now when it's evaluated for three objects, it becomes 3 separate commands.