Check your flash manuals and read some reference over the net to see how HSS works. HSS fires multiple short small burst in quick succession to illuminate object. So distance do count.
That's because u have not used it in a situation where the background light is very very strong... if u have a shutter speed of approx 1/2000 or faster u will find that the flash coverage will fall below 0.5m... u can use M mode and try.