This issue with selecting the last charcter is specific to how a user selects the last character — if you mouse-drag the last word; intending to selecting all the chracters in the last word, AE will not allow the last character to be selected. A few workarounds include the following simple procedures -
1) double-click on the last word to select the entire word, including the last character
2) mouse-drag the last word, from the first character until you reach the second last letter. Then, hold down the DOWN Arrow key to include the last character into the existing selection.
3) With the Text Tool's selection within the Text Box Area, CTRl+A to select all characters including the last character.
I believe this bug is fixed in the Public Beta Release. Meanwhile, you have these solutions to work with.
Motion Graphics Brand Guidelines & Motion Graphics Responsive Design Toolkits