Cloning Repositories not working

Hi, I've set up node-red on my Windows machine and am now trying to clone my GitHub repositories using the projects feature. The issue I'm getting is that if I try to use the "git@github.com:username/repo" URL I'm getting an Authentication failed error - I've checked all my SSH Keys, and I've made sure I added them to the SSH agent. If I try and use the "https://github.com/user/repo" URL it gives me a loading icon for a while, and then gives me an entirely blank project with no files. I also can't seem to delete the folders it creates.

Anyone had any similar issues on Windows?

Thanks,
Gregor