No problems for me over the last many months. I've always used Audacity to export MP3 from WAV format, using the highest bit rate of 320Kb/s for best quality.
Some recordings are posted well below that bit rate, and they often suffer for it. It's a shame, since some of the performances are quite fine and deserve the best audio quality. Once you set up the parameter once in Audacity, it remembers the quality setting until you change it again.