The PHB (p. 240) states as part of the Find Familiar spell that:
As an action while it is temporarily dismissed, you can cause it to reappear in any unoccupied space within 30 feet of you.
Say the wizard is outside a locked vault or a locked room of some kind. Can he use this method to cause his familiar to appear inside the locked area?
Best Answer
According to Jeremy Crawford in the Youtube video Dragon+: Q&A with Jeremy Crawford, 10/30/18, RAW says it is possible, and the targeting rules don't apply.
Transcript of video section (28:35–31:09):