We've recently noticed that users logging in using emails are having issues when they use camel case but it works fine when all lower case.  We haven't changed the configs so

case_sensitive = preserving​

has not changed.  Could the behavior have changed with a recent update.  We are running version 1.15.2 (sssd-1.15.2-50.el7_4.6.x86_64​).  This did not used to be the behavior.  Is there some other config that we now need to enable to allow the previous behavior?