Acceptances for meetings showing up on iPhone, and web but not in Gmail Inbox Outlook for Mac.

All of a sudden, when I send out invites for meetings, the email acceptances from the participants don't show up in my Outlook Inbox on my Mac. I am receiving the email acceptance on my iPhone and I can see it on my Gmail web account. Also if I go into the item on my calendar I can see if someone accepted or not. I never had this issue until a few days ago.