I’ve tried transferring from https://wallet.nkn.org/ to several exchanges and a new wallet and always get invalid recipient address, what am I doing wrong? Any insight appreciated. Thanks
Exchanges and external wallets only accept NKN (ERC-20) tokens, not NKN Mainnet tokens which is what you would have in your NKN Wallet.
Refer to NKN-Token-Swap for instructions on how to swap your Mainnet tokens to ERC-20.