seems like they don't send the kind 9735 to the correct relays.
So they're not using the zappees relays? Which ones are they using?
It's in the NIP57 Spec: Once the invoice is paid, the recipient's lnurl server MUST generate a zap receipt as described in Appendix E, and publish it to the relays specified in the zap request.
So they aren't?
it was being sent to the relays, just not the correct kind. it's fixed now on v.0.5.6