screen shot, please....
The shift key works OK here, but I'm seeing the same lack of reporting an angle.
Try trashing your prefs to see if you can restore the Shift key functionality (and if it doesn't, tell us the version of ID and your OS). See Replace Your Preferences
The fastest way I know to make a line horizontal or vertical is to use the Direct Select tool to select one end point, the copy the x or y coordinate value. Select the other end point and paste the value.
Did you ever figure this out? It's driving me insane...