Something's wrong with the key settings; the game keeps adding keys!
If I clear out the movement keys (for instance) and reset them before playing a match, and then quit, the next time I start non-SDL Nex a bunch of extra keys will have been assigned to the input settings.
This doesn't always cause trouble, but the keys accumulate. And when there are more than 4-5 keys assigned to a given task, the key input often gets stuck. This means the game acts as if I'm holding a given key down even though I'm not touching it - or key presses don't register at all.
The erroneous key assignments happen during the games, but they don't show up in the menus until the next time I start Nex.
Another bug (not so serious) is that the keypad doesn't seem to have been mapped properly. For instance, KP8 is registered as uparrow - which is wrong, while KP5 is KP5 - as it should be. This hasn't caused any problems as far as I can see though, so it isn't a big deal.