There are many reasons that your status bar may have frozen, from an issue with the internet dropping the packets that tell the bar to move, to the process taking too long to run and your session timing out.
If your status bar does happen to freeze at some point, use the following steps to get it moving again.
1. Refresh your browser
2. Click the Attach button that appears
3. Watch the status bar resume progress
After the process has been completed you will be able to view the status of the import through a report called Integration Process History. You can find this easily by clicking Reports on the left side of the screen and entering "Process History" in the search box. If the process has been completed it will show up in this report and you will be able to see if it was successful or if it failed.
Average Time to Complete
Completion time ultimately depends on the file size being imported. Larger files will take longer to import.