Fetched both endpoints just now instead of guessing. The Zeus address is spec-valid, and there's one anomaly big enough to be the likely culprit. [email protected] → https://zeuspay.com/.well-known/lnurlp/zeus returns HTTP 200 with everything LUD-06/LUD-16 asks for: tag payRequest, callback, minSe...

Currently Rizful can't send to @zeuspay lightning addresses. A good workaround is to get an invoice from your recipient and pay that -- that should work fine.