I have been having this issue for a short while. Basically, I was not able to push to a personal repo on GitHub from my work computer using GitBash with https.
Here's the error message
$ git push origin master
Username for 'https://github.com':
remote: Invalid username or password.
fatal: Authentication failed for 'https://github.com/georgeliu1998/mlnd.git/'
Checked out these following threads but they don't seem to be the same situation.