Frequency: Currently unknown.
How to trigger the glitch:
1. Have an old, encrusted level 25 character.
2. Try to chose a profession via iPad instead of computer.
The quest is accepted on the iPad normally, but then the character who is supposed to place the character in the profession says that they have already chosen the profession, when they have not. This loses the profession quest - and all the opportunity and misery that having a profession entails. (The Aetherlight is very realistic.)
The advisory: If you have an old character, get a computer to choose a profession. Also, if this glitch is affecting more than old characters and iPad users, please speak up! Thanks.