Permission denied (publickey) on AWS instance - amazon-web-services

Question

I'm trying to shell to an AWS instance using ssh with public key as shown here:
https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-key-pairs.html#having-ec2-create-your-key-pair
https://docs.aws.amazon.com/systems-manager/latest/userguide/session-manager-working-with-sessions-start.html#sessions-start-ssh
I've read every StackOverflow post on this topic and tried everything suggested all the way down through every comment.
I've made sure to do as AWS recommends with chmod 400 my-name-nr-managed-aws-services-company-name-us-east-1.pem and the .pem file resides in the ~/.ssh directory which has 755 permissions.
My verbose output for the connection not being successful is as follows (with real addresses obscured):
~ % ssh -v -i .ssh/my-name-nr-managed-aws-services-company-name-us-east-1.pem ubuntu#ec2-1-234-567-890.compute-1.amazonaws.com
OpenSSH_8.1p1, LibreSSL 2.7.3
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 47: Applying options for *
debug1: Connecting to ec2-3-234-567-890.compute-1.amazonaws.com port 22.
debug1: Connection established.
debug1: identity file .ssh/my-name-nr-managed-aws-services-company-name-us-east-1.pem type -1
debug1: identity file .ssh/my-name-nr-managed-aws-services-company-name-us-east-1.pem-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.1
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.6p1 Ubuntu-4ubuntu0.3
debug1: match: OpenSSH_7.6p1 Ubuntu-4ubuntu0.3 pat OpenSSH_7.0*,OpenSSH_7.1*,OpenSSH_7.2*,OpenSSH_7.3*,OpenSSH_7.4*,OpenSSH_7.5*,OpenSSH_7.6*,OpenSSH_7.7* compat 0x04000002
debug1: Authenticating to ec2-3-234-567-890.compute-1.amazonaws.com:22 as 'ubuntu'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: ecdsa-sha2-nistp256
debug1: kex: server->client cipher: chacha20-poly1305#openssh.com MAC: <implicit> compression: none
debug1: kex: client->server cipher: chacha20-poly1305#openssh.com MAC: <implicit> compression: none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:vQd/zj9vB89/NevF0gtTAyM+hWVNLAs0JONpLcXvZ/I
debug1: Host 'ec2-3-234-567-890.compute-1.amazonaws.com' is known and matches the ECDSA host key.
debug1: Found key in /Users/myname/.ssh/known_hosts:12
debug1: rekey out after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: rekey in after 134217728 blocks
debug1: Will attempt key: .ssh/my-name-nr-managed-aws-services-company-name-us-east-1.pem explicit
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519,ssh-rsa,rsa-sha2-256,rsa-sha2-512,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521>
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey
debug1: Next authentication method: publickey
debug1: Trying private key: .ssh/my-name-nr-managed-aws-services-company-name-us-east-1.pem
debug1: Authentications that can continue: publickey
debug1: No more authentication methods to try.
ubuntu#ec2-1-234-567-890.compute-1.amazonaws.com: Permission denied (publickey).
I also did ssh-keygen -R 1.234.567.890 to regenerate the keys which returned
# Host 1.234.567.890 found: line 12
/Users/myname/.ssh/known_hosts updated.
Original contents retained as /Users/myname/.ssh/known_hosts.old
but that didn't help either.
Any idea what I'm missing?