For reference and transparency: We have created this report on Apple Bug Reporter on 23 Feb 2016 here:

When creating a task list with MKCOL/MKCALENDAR, the calendar-color is ignored.

Steps to Reproduce:

  1. Create a task list (supported-calendar-component-set only VTODO) with MKCALENDAR or Extended MKCOL. Send along a calendar-color.
  2. The calendar-color is ignored.

Expected Results:
The task list should have the color from the MKCALENDAR request.

Actual Results:
The color from the MKCALENDAR request is ignored and the task list is assigned a random color.

Current iCloud (23 Feb 2016)

This DOES work for calendars with supported-calendar-component-set set to VEVENT only. It doesn’t work for task lists only.

direct MKCALENDAR/MKCOL requests (curl/command line)