TomWeaver999 wrote:
Seems to me a few Universal actresses, like Susanna Foster and Gloria Jean, said in interviews that they were held back, maybe because of some behind-the-scenes Deanna Durbin string-pulling. I'd like to think that's untrue.

Durbin didn't like most of her roles and would have gladly given them to Foster and Jean.  It is reported that she said the dark Christmas Holiday was her best film.  But the fans wouldn't accept her in such fare.  They wanted the happy, singing Deanna.