We are sorry that you faced this issue.
Commvault compares user GUID and updates information.
Could you please do the following.
1. increase debug level of Evmgrs to 5 (Open commvault Process Manager->go to Logging tab->you will see EvMgrS in Module column. Please set debug level to 5).
2. Login with the said user.
3. Once you get an error. Please copy Evmgrs.log (you can find commvault install directory in 'commvault Process Manager' General tab. Log directory would be one level above Base directory).
4. Go to Commserver client. Right click->All Tasks->Send Log Files. In Commcell Information tab please use commserve Data base and submit it.
5. Please let support know to forward it to us. (Reference: Mrityunjay Upadhyay, Development)
Please let us know in case you need help with above.
Thanks and regards