Hi, @martin.m.riley. I’m not sure why you are using sudo as it should not be required. If fact, I think it could be the source of the problem.
When you run netlify lm:install it configures the Git credential helper - for the user that runs the command. If you are using sudo (a command that changes the user) then my best guess is you are configuring it for some other user (root maybe).
You should run the netlify lm:install command as the same user you will be using to interact with Git and the Netlify CLI tool. Also, this command should then add a source command to your default shell configuration file (like .bash_profile or .zshrc). Please check the appropriate file to confirm that line is being added.
Please see this post for an example of the source command. If that doesn’t resolve the issue, please let us know.