回複：聽說H1B從加返美必須簽證，30天不行了

As of yesterday, 沒有誰有這方麵的消息或經曆
How did your company get that info?
A new rule like this is usually released months before taking effect. And no such rule is announced yet.

However, a 1.5 years old rule said that if you apply visa in Canada and got rejected, you can't re-enter even if you have valid I-94.