Shooting moving subject (walking) at f/1.8 - poor hit rate in indoor light

mrwilkins wrote:

Have you tried Auto Area AF in AF-C mode?

That particular mode includes face detection, which might give you better results in a case like this. I believe it's somewhat biased toward focusing at the nearest point on the subject, in which case you might be focusing on the tip of the nose rather than the eyes, but for a walking subject it's worth a shot.