How can I change the calendar that an event, added from Mail, is attached to?

Question

When I double-click an attachment from Mail.app and it gets imported into the Calendar app, I am unable to change the Calendar that the event is in:

However, items that are created from within the application themselves can be changed without issue:

I am also unable to edit them or add notes as well.

Furthermore, these events were previously not syncing and now appear to be—although the app on my phone has to be open for syncing to occur. (At least, it doesn't seem like they are there. i.e. I don't get notifications unless I go and check my calendar.)

I have already:

1. Ensured that the email addresses are attached to my contact (the "Me" one).
2. Tried deactivating and re-syncing iCloud.

This might be the combination of a couple of different issues, but I guess the big question is, why can't I edit or move these events?

Answer 1

You should be able to change the calendar it's in, so I don't understand why you can't do that, but I have encountered events I could not edit before & for me, it turned out to be the fact that the event was owned by someone else (even though I imported it on my personal calendar).

I found out that by opening up the .ics file in Text Edit.app and removing the lines which signify ownership before importing, I could edit the event just fine in the Calendar app. Just removed entries containing ORGANIZER, UID:, ATTENDEE, and/or PARTSTAT. Save and then double-click the edited file.

I created a folder action for it, so all I have to do is drop the .ics file in the folder to import an editable event.