I now have integration with the contract's source code in GitHub, and I validated that one on EtherScan, too. Contract 0xb12b339... created on the Rinkeby testnet Apr-24-2022 03:04:05 AM +UTC.

Under some conditions, it may help to refresh the page. I once had an issue when I returned to the same instance of a similar page after 18+ hours and didn't hard refresh. I suppose I could write a timer or onfocus() or something to account for this, but let's see how testing goes.

I won't give as dire a warning about this being test-only because I don't suppose anyone is going to mint random NFTs, especially for 0.08 of real ETH. Given that the contract isn't deployed to mainnet (real / live), it won't work anyhow.

Note that I was told that a 2 button mint is more conventional than a 1 button.

My main doc page and the other versions. GitHub repo with this code