What implementation are you using to produce Zap Receipts? Actually the zap receipts ARE being generated, but they're not being put on the relays requested in the Zap Request, seems you are only putting them on the Damus relay...
Discussion
I'm using nostr:npub1getal6ykt05fsz5nqu4uld09nfj3y3qxmv8crys4aeut53unfvlqr80nfm Hub with the default relay. Thanks for doing this research. Any other info I can provide to help?
ok seems to be working now, maybe it was a transitory issue