A friend of mine use's console commands as he likes a chilled build too.

But he did once mentioned to me that some people missed the - which is why i mentioned it,

but if that's not the case then maybe F5 needs a clean or maybe your keyboard is a gaming one (i use a logitech which has a gaming mode which disables some keys at a button press)

i just ran a quick check and it works fine for me, so i don't know what else to say if launcher code is correct then F5 should bring up dev commands page if not you have a keyboard problem