I agree with pp comments about being right on Ferry road, which is loud and congested with limited parking. People will view it because the flat inside is beautiful, but may well be deciding that the location is a deal breaker for them.
I live on a similarly busy street and expected when we viewed our flat that it would be a hard no because of the location - only to discover I loved it and could live with the inconveniences (which turned out to be much more minor than I expected). I'm not kidding myself that everyone thinks similarly though, so if we want to sell I'm expecting it to take a while!
I think if you want it to sell fast, you might want to move to fixed price a bit above the Home report valuation?
That said, weather in Edinburgh has been very gray and miserable up until this week, so maybe the start of spring will get things moving a bit!