I seem to have an issue with the properties that autofill to sometimes randomly get unfilled somehow even when the UI reports them as full. To fix it I usually just have to redo the auto-fill after restarting the CK or repeatedly setting and reseting them.

When it happens the log says this type of error
warning: Property X on script Y attached to QUEST (ID) cannot be initialized because the script no longer contains that property

And then it goes and the entire script fails as everything is not intialized properly.
error: Cannot call FUNCTION_NAME on a None object, aborting function call