It actually works, what’s bugged is that the autorevive buff icon doesn’t show under the character health bar with other buffs anymore.
I think those echos just need to be reworded. Instead of saying revive, it could simply say prevents death. Saying revive creates an expectation that you will see a death and resurrection sequence. What happens instead is that you don’t die and have your health reset, which can appear like it’s not working, especially because things like being staggered do not reset. A great example of this is when echo knight does the four spins followed by the overhead attack. This does tons of damage and quickly staggers, which can essentially eat up all your revives in one attack sequence. First hit kills you and resets HP, second hit staggers and kills you, resetting hp again, and the third hit finishes you. This can easily look like revives are not working, but you survived two hits that would have normally killed you. It just feels like you got lucky and didn’t die rather than the echo saving you. This has been discussed elsewhere. A rewording would help, but they really just need to be redesigned. Reviving should give you a chance to recover from attacks. Right now, getting caught in a chain can make them useless.