There's no Add User option in my client's QBO.

Hello,
 

I’m unable to add the client’s email address back to the Users list and would appreciate your assistance.
 

Background: We mistakenly assigned the wrong Primary Admin to the account. Under the Users list, both the former Primary Admin and the client were listed. To correct this, the former Primary Admin removed the client user and then added me as the correct Primary Admin.
 

However, after logging in and attempting to re-add the client, I no longer see an option to add them back to the account.

Could you please advise on how to restore the client’s access and re-add them to the Users list?
 

Thank you for your assistance.