My Musixmatch is also not working. I have a computer from my school that has fire walls and proxys, but I'm the only one that seems to have this problem. All of my other friends with desktop app for spotify have working musixmatch, but im the only one with this problem.
It says that it couldn't find the lyrics or that the lyrics don't work. The ironic thing is that it works in my phone, just says that it doesn't have the lyrics in the computer. (I have a mac, and an iphone).