The result was: his Ooze got +1/+1, he got 1 life, but Voice of Resurgence still came back to the battlefield. Is it a bug? I think this is fairly similar to Rancor mechanics.
That should not have happened. If the creature Saffi targeted gets exiled from the graveyard with her delayed trigger on the stack, the ability will not continue to track the creature. This is true for any reanimation trigger.
603.7c A delayed triggered ability that refers to a particular object still affects it even if the object changes characteristics. However, if that object is no longer in the zone it’s expected to be in at the time the delayed triggered ability resolves, the ability won’t affect it. (Note that if that object left that zone and then returned, it’s a new object and thus won’t be affected. See rule 400.7.)
I had a Saffi Eriksdotter in play and sac'd it targeting my Voice of resurgence, it resolved, and then I sac'd the voice with my Viscera Seer. When the voice hit the grave, he activated Scavenging Ooze's ability targeting voice.
The result was: his Ooze got +1/+1, he got 1 life, but Voice of Resurgence still came back to the battlefield. Is it a bug? I think this is fairly similar to Rancor mechanics.
603.7c A delayed triggered ability that refers to a particular object still affects it even if the object changes characteristics. However, if that object is no longer in the zone it’s expected to be in at the time the delayed triggered ability resolves, the ability won’t affect it. (Note that if that object left that zone and then returned, it’s a new object and thus won’t be affected. See rule 400.7.)