Me too. My Mac and my iPhone are syncing just fine with iCloud when I manually enter events. However, the problem occurs when I try to accept an incoming email invitation. This is a big problem because these days a lot of people don't show any meeting information int he body of the email - they just send the invitation and expect it to work.
I am having this problem too...very frustrating, I keep having to hit ignore but it keeps reappearing. Here is the message:
The Server responded with an error.
Access to “FAMILY” in “Family/Home” in account “iCloud” is not permitted.
The server responded:
to operation CalDAVWriteEntityQueueableOperation.