SSH issues

Hi all,
I’ve just started using CircleCI to deploy code for me for personal projects. I have managed to get my config to deploy when using the circleci local execute cli but pushing it it always falls. I have tweaked the config as below to use the projects SSH key.
I generated a new SSH key and uploaded to the " Additional SSH Keys" section. When uploading the key I set the hostname to “my-server.net” (changed for obvious reasons). I then used the fingerprint that the web page showed and added to the config. I can log into the sever I need to using the key in question.

When running after a push it gets stuck at:
The authenticity of host ‘my-server(123.123.123.123)’ can’t be established.
ECDSA key fingerprint is SHA256_VALUE.
Are you sure you want to continue connecting (yes/no)?

I then stop the job and then re-start allows SSH access to the run.
When I try to ssh in from within CircleCI I get the error:
username@my-server: Permission denied (publickey).

Can anyone suggest what I’m doing wrong?

version: 2.0
jobs:
  build:
    docker:
      - image: cimg/base:2020.01
    steps:
      - checkout
      - add_ssh_keys:
          fingerprints:
            - "my key fingerprint"
      - run:
          name: "Create build"
          command: tar -czvf /tmp/build.tar.gz .
      - run:
          name: "Upload to remote server"
          command: scp /tmp/build.tar.gz username@my-server:~/
      - run:
          name: "Install build"
          command: |
            ssh username@my-servertar -xvf build.tar.gz -C /var/www/vhosts/my-server/
            ssh username@my-server"cd /var/www/vhosts/my-server/ && composer install"
      - run:
          name: "Reload NGINX"
          command: ssh my-serversudo service nginx reload

:wave: It seems that you’ll need to add the SSH authenticity key for the host, which we have detailed here: https://circleci.com/docs/2.0/gh-bb-integration/#establishing-the-authenticity-of-an-ssh-host, to bypass the “The authenticity of host ‘my-server(123.123.123.123)’ can’t be established.” error. It’s interesting that the SSH key isn’t able to be used for SSHing from the job - are you able to verify the key is actually located within the ~/.ssh directory within the job?