I'm not receiving my husband's calendar invites

When my husband creates an appointment on the Calendar app on his iphone, he adds me as an "invitee" by selecting my email address (which is a gmail address). However, I never receive an invite via email nor does the appointment show up on my Apple calendar app (on desktop or iphone) or on my Google calendar. I receive invites from other people all the time. I have checked my spam folder and invites are not going there. It is maddening. Any ideas?