Something similar is happening to me for the Mythic difficulty. I click the button to enter, my entire screen goes orange and pink, and before I can take 2 steps forward, I’m immediately kicked out of the worldsoul memory event. I don’t even get to attack anything.
I lose my 5 radiant echoes, and am given a flat 200 x valorstones and 100 x coffer key shards. This has happened twice now in two different zones.
I don’t think I’ll bother doing these anymore since I’m not getting a chance really, and it seems like there will be no compensation from blizzard.