It is a shame that you cannot remember, because I do keep my eye out for this sort of thing. If it's a font problem, then it's not that interesting to me. And

It is a shame that you cannot remember, because I do keep my eye out for this sort of thing. If it's a font problem, then it's not that interesting to me. And most of the Unicode problems tend to be either (a) people erroneously assuming that "private use" is the same for everyone, or (b) the usual problem with code points that didn't have defined widths and suchlike in earlier versions of Unicode. But very occasionally there's something worth noting.