Hi Stefanie,
Yes, I just manually updated the button code on my site, but indeed it looks like your button code field is not updating to reflect the suggested price (&amount=) feature. Perhaps this is because I'm also using optional variable fields on the item, so the add to cart code is a form and not a direct link - doesn't look like your code is adding the amount to the form code. :)
Anyway, the feature is kind of useless unless it's presented to the buyer in a manner than makes sense. In other words, without some kind of text stating that the item is free, but that the seller recommends $x amount, it just looks like either a scam, or a cart error, at least for my uses. :)
Cheers,
-Mark