Finally got the Restorative Mind Strike after many, many runs of others and it turns out the chest spawns on a part of the map where you can't access it if you don't wait until the barriers move to the safe position, because even though the barriers visibly disappear, the hitboxes are still present making obtaining any of the unique boss drops of this strike impossible without proper timing of the boss kill. No one has probably come across this yet considering how rare it is to get the strike and because it is a Playstation Exclusive :/ My suggestion would be to move the chest into the middle area where the boss dies.