User blog comment:DazzlingEmerald/The Hyuga/Ōtsutsuki Bandwagons Are Coming..!/@comment-6003865-20141031232952/@comment-25456115-20141101212055

To be honest, i think the Byakugan is vulnerable to the sharingan's Genjutsu. However, seeing the chakra flow would help them break the Genjutsu after seeing the disturbance as Genjutsu can't emulate the real world 100%. Genjutsu creates illusions that are similar to reality. however, Byakugan can see through those as it can see through objects and it can view chakra flow, which would be disturbed in the Genjutsu.