Every time I import into Edge, I see a "Your Import has failed" message during the "Updating course" step. When I then look at the course outline, it looks like the import at least partially succeeded, since the course content has updated.
The overall impact is 1) it's really unclear whether your import succeeded, and 2) you can't continue to import without knowing to log out/log in.
1. Create a new studio course instance. Export the (content-less) .tar.gz, and re-import it.
2. During import, watch the Course Import Status update. During "Updating Course", see the message "Your Import has failed" pop up.
3. Click OK. Now your user interface will show the import stuck on "Updating course" until you log out, log in again. (See https://openedx.atlassian.net/browse/PLAT-658)
4. After logging out/in again, see "There was an error with the Upload" under the "Uploading" step on the Import page.
If you do steps 2-3 using a .tar.gz with content, you can go to the course outline, where you'll see the content has actually imported and updated.