Go to an individual contact record. Click on "Actions" button and select "Add Contribution."
For a moment you see a greyed out form with the "Submit Credit Card Contribution" link visible, but then that disappears and the offline contribution form pops up with no choice for submitting a live credit card transaction.
The work-around is to not click "Actions" but rather click the "Contributions" tab. There the link "Submit Credit Card Contribution" is present and working.
I was able to reproduce this bug on the current demo site.