http://www.blazelabs.com/l-vacuum.aspThat is just one of many such experiments. Lifters have yet to pass any functional test in a vacuum. Speculation that there is a propulsive effect beyond ion wind is just that, speculation. All evidence points to it being merely ion wind.
You
can make an "ioncraft" for interstellar flight - there are several proposed ideas and ion-jets/thrusters notwithstanding they require a sail or collector array many thousands of miles in diameter. All use some reaction mass, be it interstellar hydrogen or high-velocity particles ejected from the sun. You just can't break the third law of motion with any known
practical means. Lord knows I wish you could.
The reason people keep looking to electromagnetic ideas for antigravity is because of
this, which relativistically couples with gravity. Physics has banged its head against that relationship for more than 100 years, and largely fruitlessly. For antigravity to exist, some mechanism of fundamentally changing spacetime itself needs to be found.