Filth boss tracking?

Never had a problem with her before but just had an encounter where her roll/flip into a smash tracked me down while on Rhoa with 30% movement speed. 2nd attempt i tried to roll off at last second but still like a heat seeking missile i couldn't avoid her. wasted 3 more attempt to get 1 shot by her. I've done her in campaign and multiple maps but this one encounter wasn't like the rest.