Farming glorious vanity (Xibaqua)

Hey all legion question. I'm trying to farm a glorious vanity (xibaqua) jewel in ssfhc. I started doing 3 way legions and found 4 glorious vanities in about 7 tries (no xibaqua). I switched to 4 ways and found none in 5 tries. My strategy is basically just kill viper napuatzi (vaal boss) and reset and kill him again over and over not worring too much about the other bosses. I probably kill him 5-6 times each 4 way. Am I doing something wrong that all of a sudden I stopped finding glorious vanity jewels?