I think it's your "save for later" action that's causing the purchases to not track correctly. This is an Amazon issue, not a JetBlue one.

When I shop on amazon, I look for what I want, then open an incognito window, sign onto TrueBlue, then click through to Amazon and sign in there. Then I copy and paste the item titles from the regular browsing window into Amazon in the incognito window and add to my cart from there. I track all of my purchases and I have not had a single one fail to post.