You could use the Etherscan API for search the NFTs of an address like:
https://api.etherscan.io/api?module=account&action=tokennfttx&address=" + address + "&startblock=0&endblock=999999999&sort=asc&apikey=" + key
Where "address" is the address you want to retrieve and the "key" your API key (if you don't provide an API key, the returned nº of NFTs is limited).
If ENS gives you 0 NFTs, the address you are looking/searching (more probabily the ENS smart contract address) aren't the same that emits the NFTs. Looking on Etherscan it seems that the address that emits the ENS NFTs tokens is: 0x283af0b28c62c092c9727f1ee09c02ca627eb7f5 (but you should do your own research).
You could try with:
That returns a lot of NFTs results (more than 9999). Hope it helps!