Yeah, the problem is that SDL never raises the keyboard event for the QuestionMark code on my keyboard (and probably most US keyboards), so I had Shift + Slash mapped to show keybindings. I just fixed this issue, so next release shouldn't have any of these problems.
You can also add the keybinding yourself by editing 'keys.cfg' and adding an another [ShowHelp] entry with the code=QuestionMark and modifiers=None.