If it hovered with no forward airspeed there are several possibilities:
1. You had a headwind.
2. You were looking at the airspeed guage and it was designed to bottom out above the VSTOL speed.
3. You were dreaming.

VTOL is simply not possible in a fixed-wing airfile in FS...no ifs, ands or buts...
Which payware Harrier were you flying?