In round 1 of the elimination tournament https://online-go.com/tournament/2492 , some players with 5W1L advanced while the others were eliminated. The pattern looks pretty random.
The strangest cases:
fabu with 6W is eliminated while bahytych (5W1L in the same group) advanced.
sekoj, skydyr and Samick were in the same group with 5W1L, but only sekoj advanced.