eNuts can't access your Nostr account DMs due to its lack of access to your private key. Instead, it generates a new key for sending Ecash. When you send Ecash via Nostr, the recipient gets it from your new eNuts public key. If the recipient replies to that DM with an Ecash token, you will be able to claim it in the wallet. It is confusing and we're working on a secure solution to allow private key imports.