Is there a way you can affect a single player only even though every player is inside the blocking volume?
Yes, you can use “.AddToIgnoreList(Agent)” for a Blocking Volume and run it on any agents that you want to exclude. I have used this and it works.
I don’t think the guy was talking about Barrier Devices but Blocking Volumes which are used to set a player to first person view for example.
I guess you could try to move the blocking volume into your playing area with a sequencer that plays on instigator only!