Yes, I'm seeing this too. One of my customers on Office 365 is experiencing the issue for just two of their users. Outbound emails are fine but these two users can't receive any inbound mail. Even sending an email from their mailbox to themselves doesn't arrive. I've logged a call with Microsoft about it but yet to hear anything back.
I don't think it's ISP related as this customer is only seeing the issue on two of their users.