Import Data Users

I am trying to import users data into the cart to update their user groups. I am using the same format as the export users and changing the User group IDs column and then re-uploading. Apparently the upload doesn’t like the format and simply times out and will not update the user group id or status.

Does anyone know how to do this or the correct format?

The format I am using is: 1:A;2:F;3:A; etc… (same as the export)