I too was able to get a spot for a couple seconds -- BUT ---
Things -- You have that tornado tube project. Plug it up and set it for this. The tube can provide a small, stable condition for this with the fans off.
Several variables determine how long the optical trap will last:
1. Sharpness of the focal point -
Ideal particle stability is a wide beam focused to a point
Collimated to a thin fine beam will allow several traps along the beam (like my photo).