Same here, I only can walk to the upper/lower right (diagonal) by pushing the analog stick to the upper/lower right. If I push the stick to the right I walk to the left.

Tested with OpenBOR and GIJoe Demo.

If I set the envvar, I can assign the directional buttons and walking to each direction is working fine.

I also tried MultiRacer, and with the envvar set I can use the directional buttons and L1 and R1 in the controls menu.
But without the envvar I can setup the analog stick for accelerate, brake, left and right but the directional buttons and L1,R1 are not recognized!

And steering with the analog stick works good in this game.

So I think the bug with handling the analog stick is in SDL!?

Would be nice if one could use both, the directional buttons and the analog stick at the same time, also the right stick and L2, R2.