ML 10.8.1 Calender only syncing one-way

Question

Okay, so the problem is that my Mac Calendar is not syncing its events to iCloud. However, it does work the other way around.
My e-mail and contacts synchronization is working just fine.
So:
Event made on Mac Calendar -> iCloud / iPhone / iPad does NOT work
Event made on iCloud.com / iPhone / iPad -> Mac Calendar DOES work
Troubleshooting I’ve done (and please read carefully):
*Verified that I’m not accidently writing in a local calendar on the Mac
*Verified that I’m not out of space; I have 21,81 GB available
*Verified I’m really looking to the correct date & time
*Created a new, empty, calendar to test with; no solution
*Hit the Sync button manually a thousand times
*Passwords are correct and even changed them, just to be sure
*A fresh install without restoring any back-ups. After letting iCloud sync, the problem still persists!
So once again: Even on a clean install of Mountain Lion with only iCloud logged in, the problem is still not solved.
Events created on the Mac calendar are not syncing to iCloud.
When I look into the Console, I see several error messages, which are not recognized by Google nor do I know what it exactly means.
An example:
31-08-12 19:02:04,251 CalendarAgent[3467]: [com.apple.calendar.store.log.caldav.queue] [This change request has been materialized into a queueable operation before.  Change request: [<CalManagedMessageChangeRequest: 0x7f91634e5d50> (entity: MessageChangeRequest; id: 0x7f9164271af0 <x-coredata://A50C70DE-D8F0-4D80-997C-603F5B8FDEEF/MessageChangeRequest/p2> ; data: {
    dependencies = "<relationship fault: 0x7f9164314b50 'dependencies'>";
    dependents =     (
    eTag = nil;
    error = nil;
    firstMaterialized = "2012-08-31 07:27:19 +0000";
    localUID = nil;
    principalUID = "DCA3CB80-07A7-4815-BAC4-36C0244D7F63";
    scheduleTag = nil;
    sequenceNumber = 2;
    serverFilename = "d4a2d44340fb7c5f63b639dd6830c976ee55656d.xml";
    sharedUID = nil;
    sourceUID = nil;
    type = 21;
})].  First materialized date: [2012-08-31 07:27:19 +0000]. Existing error: [(null)]]
I'm using a MacBook pro 7,1 with a legit version of Mountain Lion.
What sorcery is this?

Answer 1

I can confirm it probably has to do with my account.
I've just removed all shared calendars, and on the new account with my gf's iCloud everything works smoothly.
I've also removed all shares of my own calendar, leaving only my personal calendar. However, it still does not work.
So your suggestion is to now export all calendars, then remove all calendars, and then test with new calendars?
But what do I do if it's still not working then? Because then I have no calendar data on my devices, and then I'll probably die because I'd even forget to breathe without my agenda.