Can't use my ult and tinker when pressing space.

So i always have been able to cast my ult or put a ward down while pressing space but recently it just dosn't work any more . When i press space bar it just dosn't allow me to use ult or put down ward only if i let it go but im used to holding it in fights to find my champ. Its quite anoyying and i cant seem to find reason why this is happening . Please help ! :(