Issue in synchronization between active directory and ISE

There’s an issue that surfaced the last couple of days. We’re using dot1x for wireless authentication. The issue is, when I create a new username in the active directory, the ISE doesn’t know anything about that username until the next day. The user can’t connect to the wifi using that username until 24 hours or so have passed. Synchronization used to happen instantly but now it doesn’t. Can Anyone help me with this?