I play with 800x600 resolution, and blatantly legions lite. This glitch happens when I have my Plasma out. The big white block rarely moves unless I'm jetting in the air and pointing my reticle down at a weird angle.
Funnily enough, I encounter that one too. But, and here comes the twist, only when other people use it. I usually play first person, and couldn't replicate it when playing on my own. Nonetheless, I do see it flicker in crowded games from time to time (no LL by the way).