Why are only my basic cable channels and ESPN working? All other channels just give me the black screen with the channel logo and three loading dots.

Since last week, only a few of my channels have been working (basic cable channels, ESPN, and a few spanish-language channels like Univision). All other channels will not load and just give me the black screen with the channel logo and three loading dots. I have received online help from Cox twice and they have reset box remotely and I have an appointment set up for Saturday. Was wondering if anyone else has had this problem? Just a defective box?