Dude! I had the same issue during my initial playtesting... it IS a bug, but it happened to me just 2 times out of like 50-60 times that I tried to reproduce it. And I prayed so hard that nobody ran into the issue and ditch the game. Thankfully you gave it a second try!
I tried making the cancel with right click, it is actually in the code but disabled. Because I noticed that after I cancelled the shot, I ended up dying anyway. Maybe skill issue lol, with quick right click -> left click transitions to make it work.
Thank you so much for playing it!