In our instance of Jive we have seen some unusual activity when it comes to Usernames. Initially, we ran into issues because they are case sensitive (rare these days) and Jive would always put the email as the username and make it all lowercase.
Now, that is not happening until after the user logs in once and then it moves everything to lowercase causing some confusion and one of our users even had to reset her password not realizing what had actually happened.
Why is the username case sensitive and is this a bug that initially it does not change the username to lowercase but after initial login it does?
I'm sorry to hear about the case sensitivity issues you're seeing with the username. I'm not immediately aware of any bugs around this, but this may require some troubleshooting. I would recommend submitting a support case in your private Jive Community customer group. If you're not familiar with the case submission process, please reach out to your community manager for guidance.