Nocturne R + Sweeping Lens Interaction?

So I was playing against nocturne, and as i was trying to remove wards he ulted and the wards i was destroying became untargetable with lens particle's showing around them(visible in replay, invisible in-game). As far as i know his ult lowers vision distance and disables map,it does not give wards "untargetable" . Forced me to use my pink. :/

IS this an intended interaction or a bug?