Unfortunately, I have a similar problem but no resolution. I'm using the latest Twitter widget and have checked, double-checked, deleted and added the widget back and still no joy - all it shows is "My Tweets" and the link goes nowhere. Both on Chrome & FF the Widget is there but just shows "My Tweets" with a dead link.
I've checked the 18 character Twitter ID - all numeric, no char - as shown when you edit the Widget on Twitter.
I've even checked the underlying element in the Chrome browser and it has the correct "data-widget-id=" as shown on Twitter and the Widget setup.
The blog in question is An Accidental PM