I have a public submodule:
[submodule "submodules/quickstart-microsoft-utilities"]
    path = submodules/quickstart-microsoft-utilities
    url = git@github.com:aws-quickstart/quickstart-microsoft-utilities.git
It does not init or produce any errors. I have keys in Github but this is public. The main repo that references the git submodules is private, but clones fine. Changing it to https works fine:
[submodule "submodules/quickstart-microsoft-utilities"]
    path = submodules/quickstart-microsoft-utilities
    url = https://aws-quickstart/quickstart-microsoft-utilities.git
Cloning via SSH on this public repo outside a submodule works fine:
git clone git@github.com:aws-quickstart/quickstart-microsoft-utilities.git
What gives?
 
    