kevinblue360: Thanks for the suggestion, but I tried already. The bar gets about half way then starts going back down.
cooper: go to the game options and see if your mouse is all the way up? I had an issue where in one part of the game, I needed to adjust the mouse responsiveness to complete the task. Just a suggestion.
kevinblue360: Also, try disabling "Difficult QTE" (don't know if it applies here) and reduce your resolution for that particular moment.
The resolution bit may sound crazy, but it apparently works for some folks. Has something to do with refresh rates etc, I think.
I also don't recall reading if anyone had luck with it, but you could try remapping your "Fast Attack" to a key for just that part. I believe that would make the QTE require you to quickly tap a key instead of your mouse. (Don't wanna get spoilerish, but if this is the solution, it may cause trouble when you hit the first boss.)