May I ask why I cannot send an ERC-721 token using MetaMask iOS app? After entering the “to” address and touching the “review” button, nothing happens, even no error messages.
However, when I using web browser extension MetaMask to send the same ERC-721 token, it works as expected.
I tried NFT on Sepolia and ETH mainnet.
Hi @71d97de8547fb085b35d and thank you for raising this. Could you please let us know what MM version are you currently using on mobile (You can find that in Settings > About).
Thank you for the swift reply. The MM version is v7.60.4 (3255)
Of course, here to help! 
Thanks for sharing the version number, in this case it would be best if you would reach out to our support team at https://support.metamask.io/ by using the Contact Support button there. They will be able to take a more in-depth look at what might be causing this issue.
Once you press Contact Support , a live chat bot will appear on your screen. It will give you an automated response at first, but insist and you should be able to contact the support team.