There could be many reasons why you weren’t able to send assets from Metamask. The followings are the common cases.
Make sure you have selected ‘Klaytn network’ in Metamask. Since Iskra wallet is a Klaytn-based wallet, transmission is available only through Klaytn.
Check the transaction gas fee setting in Metamask. Both ‘Max Priority fee’ and ‘Max fee’ must be set to ‘250’ in gas fee setting.
Please refer to 'Pioneer NFT Purchase Guide' for more information on transfer.