I think you have to tweak the walkcycle a bit. I suppose you have made a stationary walkcycle and moved the character's group layer with layer translation. This works reasonably well with the right leg (less visible), but with the left leg it shows. I have isolated a clip of the walkcycle and slowed it down by a factor of four:
When the left shoe is touching the floor, it remains there for more than one frame, while it and the character is moving forwards. However, we know from experience that when a foot touches the floor, it does not move forwards, unless the floor is slippery. OTOH if the floor IS slippery, the arms should correct the balance of the body. Therefore this walkcycle looks "odd", however you look at it.
You can either correct the walkcycle so, that the foot touching the floor remains there (so in stationary state, moves backwards, to correct for the forward motion of the body due to the layer translation) or redo the entire animation as bone animation (not using layer translation, but bone translation of the root bone instead).
The disadvantage of the latter method is that you can't simply copy the keys in the bone animation and do an independent layer translation, but have to translate the root bone of your character. If you haven't got a root bone, because you rigged your character's body parts with independent bone layers, you must redo the entire rigging of your character to have a root bone.
The advantage is, of course, that you have much more control over your character's walk cycle. However, that isn't an issue here, because the character just walks across the screen. If your character walks from one location to another on screen, with pure bone animation you can use the opportunity to do more with your walkcycle. See Richard William's
Animator's Survival Kit for examples.
I hope this all makes sense to you.
BTW I'm no professional animator, just an overly enthusiastic hobbyist.
