Put your LNURL here and see what is decoded.
https://lnurl.fiatjaf.com/codec/

Maybe your LNURL server is not serving the correct response or is not visible over https.

LNURL = a web server that is requesting a LN invoice from a node and delivered to the wallet is requesting it.
LN address = is just a human readable LNURL.

Here is a guide about using LN address in many different ways:
https://darthcoin.substack.com/p/getting-started-lightning-address
And here is the list of all LN wallets that support various LNURL types
https://github.com/lnurl/luds#lnurl-documents