There is a bug in the game demo, where texture type are not creating set up, causing footstep material types not to change correctly depending on the texture type the player character moves over.
I have created a full guide of how to implement footsteps and fix the above issue + other issues, it may help the bug you mention.
NOTE: The guide series i point towards is quite an advanced guide and will require to come away from the 101 guide series, so i suggest try to follow the 101 guide series first.
My guide series for the CUBE + Wwise:
https://www.youtube.com/playlist?list=PLwxDjxJeenFS7T8Q37JSRnLYylCb06UOI
Footstep related content is broken down into 5 parts, please see all Chapter 07 steps.
Starting here:
https://www.youtube.com/watch?v=ao35tA4JA2M&t=&index=20&list=PLwxDjxJeenFS7T8Q37JSRnLYylCb06UOI
You will also need to reference the new hierarchy changes in Chapter 04 & 05 for Chapter 07 to make sense.
Hope the above advice helps you progress