I just recently beat the Kaineng Overlook Strike mission for the turtle parts. I got all the chests and mastery point and opened them all, but I did not get the turtle part. I have the quest to get the turtle parts active but nothing. Reddit told me it's a 100% drop from the chest you get, but I didn't get it. I don't know if this is a new bug or not but I figure I should report it and possibly hope anet can fix it on my side.
Proof I beat the strike mission: https://i.imgur.com/ziM6WyU.jpg
Proof of no saddle part: https://i.imgur.com/bQhNQFf.jpg