Bulk User Upload - won't inload

MCorbin Overachievers Alumni

All -

I'm trying the bulk inload of users for the first time to add about 400 non-licensed users to my account.

I downloaded their CSV file temlate, added my user data (from a Smartsheet sheet). I have uploaded it into the Import Users screen, the "Import" button seems to be enabled, but clicking it does nothing.

Does anyone have any troubleshooting suggestions? Is there any formatting that needs to be done in the CSV file? All help appreciated :-)