I discovered there was an issue with the Vanity titles. I made the recording by date, but if you were registering 1 minute before midnight, it would expire immediately. So I have to change the system to record the time at which you set the title and also take the proper timezones into consideration. Now everything should be good.
If you login now while the title is still active – and be it for one more minute – you can keep it until you relogin again. Unless, of course, you use the /vanity check command. That will discover the expired title and remove it.