Thanks for the feedback. This was actually a deliberate choice. one of our teammates basically broke the game in testing befcuase he drew over the whole map, covering everything and released for all enemies to be grilled. We had to limit the drawing but decided to give a visual and audible clue when you are going too far.
Did you play with sound? It's an important feedback mechanism in that case.
Thanks for playing and one more thing: if your mouse is not very good - it's very tough to draw correctly, I noticed that on my laptop mouse