As if having to fill out a questionnaire in order to leave feedback for a seller wasn't enough, if you are leaving multiple feedbacks at the same time, you need to make sure every field is filled out on every single feedback. If you don't it will tell you that it's "Unable to leave feedback for one transaction" and erases everything you've written for all of them.
It's been annoying a lot of people since they brought that style feedback system into play, but, they don't listen, they just take a cut from sales and expect everyone to like it or lump it... :-\