I'm on High Sierra, using iPhone and MacBook Pro. I receive invites in my Apple Calendar app from Outlook users without problems. I get the Accept, Maybe and Decline buttons as expected. When I accept an invite it appears on all my devices without problem, but the sender of the invite doesn't receive confirmation that I have accepted or declined the invite.
I have checked that my contact card has the right email address, not sure what else to do.
Any thoughts or advice?
Thanks in advance.