Not allowing to add new user

Hello,

Per free version there are 10 users allowed. I have 8 users in my account and I am trying to add a new user. This new user is not receiving an invitation mail in order to access the system. 

To be clear, I had added 1-2 users earlier to evaluate the fitment of Lean for our organisation. After evaluation I did remove these users, but I think the user data has not been cleared on the backend, which is not allowing the new user to receive a mail.

Can you please check and fix this?

Thanks,

Mehul