I am like some who have met the kayran bug, Spoilers follow:
Mine appears like this: 3-4 tentacles chopped? Check. Ride the big tentacle? Check. Fill the QTE bar all the way? Check. Then no spacebar prompt appears. Ever. Tried all the suggested fixes I have seen on all the forums I have lurked through. Lower res, lowest difficulty. Difficult QTEs negated. Tried playing on a faster computer. Tried a new download of the game from Gamestop. Get the QTE bar filled all the time. As soon as possible, I start spamming the spacebar without waiting for the prompt. Tried hitting spacebar with only a few LMBs. Lots of different combinations of spacebar and LMB. All the same. Geralt always gets thrown off at the end of the Tentacle QTE, No extra bridge parts fall to create the ramp. There are bridge parts, but they are unclimbable.
So, I have decided I have some sort of irreconcilable bug and must request an ignominious resolution. As much as it pains me to admit defeat, I request some kind soul to try finishing the big sucker for me.on their computer. My best wishes and a hearty thank you.
File can be found at: http://depositfiles.com/files/nl9afnoyx