Exceptions to liaisons
In the following, is there no liaison between "Avez-vous" and "une"?
Avez-vous une préférence?
In addition, can you give some common examples of exceptions to liaisons?
Mille mercis!
There is any liaison between "vous" and "une". Because "vous" is a pronoun and "une" just an article.
There is a liaison between "vous" which is the subject in your question and "avez" the verb. Verb and subject are linked. And when you ask a question like english verb and subject are reversed; but you always need to show the link between them, it's why there is "-".