Hello! I’m sorry you’re experiencing an issue. Exactly what kind of ‘change state’ are you referring to?
Do you mean a presence state change (for example, from ‘available’ to ‘away’ or ‘on the phone’), or do you mean something else - perhaps that you cannot see users come online or go offline anymore?
Does this affect all users, and/or all contacts?
Have you reviewed the log files? Maybe there are clues to the cause of this problem to be found there.