@VisAgilis is absolutely right.
In your BP you re using Launch with 1000 on the Z axis but both X and Y are normalized (in the range 0-1) which means that your horizontal component is non-existent. (even if it was correct)
The cross product always returns a vector perpendicular to both inputs which means that WallrunNormal x Forward will always point up.
Try something like this instead:
Cheers!
P.S.
You might remove the unneeded components (like the forward boost) and maybe combine the parameters in a single vector instead of having them separated but it was easier to explain that way.