This works in star with a floating star point using filament lamps, because the loads, despite their large temperature coefficient, are approximately resistive for a small change in temperature, and at least are always electrically continuous. Electronic drivers are switched-mode power supplies that work at approximately constant power input so they can have negative dynamic resistance, i.e. the current falls as the voltage rises. A unit that, through minor differences in load or construction tolerance, is using slightly less current, will receive slightly higher voltage just as though they were in series on a single pahse supply. This will further reduce the current and the system will experience positive feedback, almost inevitably swinging to extreme unbalance until one unit receives too low a voltage and shuts down. At that time almost the full 400V will be across the unit that is still operating, until it decides not to operate any more! The same will occur if one unit starts up slightly quicker than another.
In summary - identical single-phase loads in star with floating star point, OK with constant resistance loads like heating elements, no good with electronic loads even if apparently perfectly balanced.
