I decided to try the 1.5 upgrade on another machine running El Capitan (10.11.6). In this case I had the opposite problem I had running in Sierra.
In Sierra, i could not add or edit the cookie list in any way. CC 1.5 showed the 'saved' cookie list which had been created in Version 1.4, but ignored that list and deleted ALL cookies, including those in 'save' list. When I trashed preferences, and started CC 1.5 with a fresh install, the cookie field was empty and I was unable to edit it or add cookies in any way.
In El Capitan, the cookie list had also been saved from version 1.4 after I upgraded to 1.5 - and I could edit that list. However, after running CC 1.5 in El Capitan, NONE of the cookies were removed.
So, for me, it seems as though CC 1.5, in Sierra, deletes all cookies indiscriminately, with no option to save, and CC 1.5, in El Capitan deletes none of the cookies at all.