icloud calendar not accepting all email addresses (@SLD.TLD)

It seems like Apple Calendar has some restrictions on the format of an email address. I can send emails to

name@company.domain or name@SLD.TLD

but when I send a calendar invite to the same address name@company.domain or name@SLD.TLD it does not work.

It works when I send invites to older style addresses such as name@company.com etc

with reference to - https://data.iana.org/TLD/tlds-alpha-by-domain.txt

I can receive events from name@SLD.TLD but not send events/invites out from Calendar on my devices