I have a work GitHub account and a personal one. First I used the personal one for test projects, then I moved on and did a repository with the other account on the same com
I got the same issue. Below is what happen in my case:
I previously made git to not ask my credential every time I talk with remote repository by this: git config --global credential.helper wincred
I resolved the issue by running the same command with "none" replacing "wincred" git config --global credential.helper none
Then git ask my username/pass again and everything go well