Ah, I never properly played the 3D era titles as I didn't like them. Of that era, I mostly played Mortal Kombat Unchained on my PlayStation Vita simply out of bordom on my commutes to and from work. The mini games were a lot more fun that the actual game .I can totally understand it in the present day, but I meant when it was first changed massively during the 3D era (but I can't remember the controls for those off the top of my head so maybe that was for a technical reason then too?). But I still don't like away-towards/towards-away inputs, I tend to fuck them up a lot. Either I've got terrible motor skills or my controllers are getting old (probably both... albeit mostly the former), but they're moves that often tend to fail to register when I try them.
Still at least we've got the vitally important 'switch stance' button to make up for it
For back, forward motions, go into training mode and do them and see if the input is registering or not. Do it slow and deliberate and also fast. That'll rule out your Controller or not.
Personally, I prefer back forward motions to quarter circle motions; I botch up the latter more (and it's totally me).