Have you looked at https://kf106.medium.com/this-is-the-biggest-nft-airdrop-ever-24b0f5cd646b ?

One of the problems is that the events in your contract are not ERC721 compliant, and the absense of a Transfer even from the zero address means that there is no "mint" detectable and hence the NFT marketplaces won't pick up your tokens until they're transferred.