Diagonal d-pad inputs (which are legal combinations of two directions, such as UP+RIGHT) are not working in Gens 2.14. When you push any diagonal direction, Gens thinks you aren't pushing any direction at all, and your character in the game does not move.
KEGA Fusion does not have this problem.
I have this exact same issue! I went to the Gens forums to report it, got re-directed to some discord group where people didn't even know what Gens was and then the admin (who seems to have the same name as the guy running the Gens site) tried to tell me diagonal movments in Genesis games didhn't happen.. WHAT THE...
Safe to say this one won't be fixed as apparently we're all just imagining things. :(