Hey Andy, hey John,
yes, you don’t really want to know what happens when your kilowatts induction motor, from one microsecond to the other, becomes a kilowatts induction generator when spinning at high speed and the current is cut off (and it cannot reach the braking chopper inside the VFD and the braking resistor (see also dynamic breaking)).
Even the Huanyang has this warning in its manual 
, only the picture that shows it is strange. The little “x” on page 5 means “don’t do this”.
On my Omron MX2 Manual, there is also the
Warning to put a switch on the input of the VFD:
