I got it! I had to keep clicking hint, then clicking all around the hint's circle rather quickly. After about 4 tries, the last target showed itself. I had uninstalled & re-installed the game and re-booted. I finally started the whole game over again, only to find the same problem. But then I started clicking as I stated above, out of frustration and it worked.

I am having the same problem - but I believe that it is because my computer, which is refurbished, was meant to be part of a network and has no graphics card other than what exists on the motherboard. Anything with intense graphics can create a glitch like this. I've had this problem with several games that I used to be able to play on my previous computer, which was not a networking one. Unfortunately, it died and at the time I purchased this one I didn't realize it had this limitation. This probably won't help you, but it is one possibility.

I wish too, that there was a skip feature for this target practice section!