When completing echoes with a party member where the reward are Tomes of Experience, occasionally I am unable to pick up some or all of the Tomes.
How to replicate:
After completing an echo with the Tomes of Experience reward while in a party with 2 members (maybe more, not tested), while party member remains in echo, portal out and spawn the reward (without collecting any of them), then have party member portal out of the echo back to the platform with the reward. Any Tomes that haven’t been picked up when your party member portals back will no longer be able to be collected.
This is true for both echoes that I pick that offer the reward as well as the random choice you are given when a party member chooses an echo.