Basically, I am trying to give multiple users access to a private group. 

I am using this module to add the security roles to the users. 

In the excel file, I have all the usernames of the users. 

Step 1 -  I upload the file

Step 2 - I select username and corresponding DNN 'username' field 

Step 3 - Select DNN role radio button,

Role settings - "Private group" 

When - "Only import updates"

And add event.

Step 4 - 

I select "overwrite Overwrite Existing Users?" checkbox

Update user based on which matching profile field (default is username) - selected Username in combo box

Update all existing user credential fields (includes username,firstname, lastname, email, password) - didnot check this checkbox

Step 5 -  finish

The security role is added successfully to all the users but, the firstname, lastname, displayname and email addresses are now blank for all these users.

How can I fix this? Is this a bug? I didnt check the "update all existing user credential fields" but still the firstname, lastname, displayname and email address fields are overwritten. Please help. Thanks in advance.