AutoCad :: Correct Command Prompt Follows Return Key

I've noticed this annoying trait in AutoCAD 2012 when drawing a polar array that I hadn't noticed in previous versions. I used to get stuck in a loop having to repeatedly enter the number of items in the array trying to get it to move on to the next command prompt of what angle of fill I required.

Example
CMD = Enter number of items or [Angle between/expression] <4>:
<Type in 20 and hit Return key>
CMD = Enter number of items or [Angle between/expression] <4>:
<Type in 20 and hit Return key>
CMD = Enter number of items or [Angle between/expression] <4>:
<Type in 20 and hit Return key>
Ad infinitum...

I then discovered that this only seems to happen when the cursor is left over the centre of the array you clicked on. But if it's moved to one side the correct command prompt follows the Return key. This isn't intuitive as you have to leave go of the mouse to input the required number at the keyboard, so it tends to be wherever you just clicked, and you end up in the pointless loop.