Hi,
Earlier the error that you were getting was due to time limit exceed. SO that will be fixed when you run it in background.
Now the error that you are getting while running in background is due to some lock object in some transports so you need to get the list of the transports and release them.
To get the list while running in background please check logs or just execute this step in dialog. Once you run in dialog you will get the list in the screen. Release all the transports and repeat import in background.
To check the log in saint use these option.
If you want to get the list in dialog.
Select the start option such that only 2 phase runs in dialog.
Hope this helps.
Thanks
Rishi Abrol