DOes anyone else face it too? I model a character and apply piped and envelope it, then half the time when I want ot give it footsteps from the motion panel, the option simply doesn’t highlight and I can’t press the button. I follow the same procedure for another character and it works. It works every time for a Biped without a mesh though, but with mesh its a matter of chance. Any help? Anything I might be doing wrong or missing?

Bibeds can be animated in one of two ways, Footstep animation or Freeform animation. It has to be one or the other, it can’t be both. Which mode you get depends on what you do to the biped. If you start animating the biped manualy, it will be in Freeform mode and Footsteps become unavailable. If you start by adding footstep animation it will be in Footstep mode.
You can however convert the animation from one mode to the other if you need to.