Invites from Google Calendar sent to iCloud+ Custom Domain email not arriving

[gypsymoth]

I have 3 custom domains set up on my iCloud+ account.

2 are newer domains and they successfully receive emails and calendar invites from ANYONE.

The older domain - which has the correct MX records set up with the email host - only receives EMAILs. It does not receive calendar invites from GOOGLE CALENDAR at all.

It's as if they get filtered out. It's really weird.

It applies to all my apple devices with mail set up. It's a backend issue

Has anyone else experienced this?

Thanks

 

[gypsymoth]

Update to this

Google calendar invites sent to a catchall email - for example, [email protected] - come thru weirdly. So the issue is isolated to the *main* email address I set up on the custom domain