The receiver will try to send to your public inbox relays. They are not going to pay for an account on Eden, so you only have nostr.mom that works there. Maybe add another public relay to that section.
I'll leave it for a while and see what happens, I've sent you a small 21 sat zap, after adding the damus relay and got no response, I've just added the primal relay to the list as well, so I'll check again in a bit.
I've seen the same, sometimes it works, sometimes it doesn't, even between two zaps to the same person. Sometimes a zap receipt shows up on nostter, but not on Amethyst. But I guess a lot of relays puke on my follow list 😆