I just got hit with this issue myself.
A customer ordered one of my pendants in polished silver. It was a pendant I'd printed before in rhodium. I've attached a picture showing that the pendant came out just fine, exactly the way I wanted, in polished metal.
Yesterday a customer ordered this in polished silver. He got back the "detail too fine" error, which I've never received on this model before. The message included that the success rate had been set to 0% for all the polished metal designs for this pendant.
I've got two big problems with this:
1) I've received no message from Shapeways at all about this. I learned about what happened because the customer contacted me via Facebook.
2) As usual with the "detail too fine" error, I can't tell what's supposed to be wrong. Did the checker think my engraving wasn't deep enough? Did they object to the parts of the engraving (it's the Sanskrit "Om", BTW) that come to a point? I don't know, and only a long and potentially expensive iterative process would give me an answer, since the "detail too fine" check only comes after an order is placed.
So we've got a unhappy customer, a confused and unhappy designer, and a mystery of why something that printed a few months ago is being rejected now.