Unable to Accept, Maybe, or Decline calendar invites received as attachments from iPhone 90% of the time

I had this same issue and the solution I found was to go into Settings > Yourname > Apps using iCloud > iCloud Calendar in Account Settings (send Receive) updated so your calendar requests will be sent from your iCloud email.

That change resolved my issue.

Cheers

Same problem, but on iMac OS 13.2.1

I’m so beyond frustrated with the same problem. Invites coming to my @yahoo.com email from another @gmail.com account come in as .ics files. I can add the invite to my iPhone calendar but cannot RSVP accept/maybe/decline. I e tried apple TEC support but after 60 minutes had to drop off the phone.

any help would be greatly appreciated!!!

If I receive a calendar invitation to my email (iCloud.com) I can see an .ics attachment and I can add the meeting to my iCloud calendar but I cannot reply (accept, maybe, decline).

If it is to another email (like outlook.com) I cannot download or open the .ics file and cannot add it to my calendar (iCloud calendar) but if I turn on the right options, I can add it to my other provider calendar (which I don’t use). However, if I open Mail on my MacBook Air, I can add it to iCloud Calendar with no problem but still no ability to RSVP.

For me it works only on my work calendar which is on Google workspace. For my iCloud calendar the only way to reply to an invitation is on my Mac calendar, like many others have posted.

This problem still persists with iOS 17. It is very inconvenient.