I also have this exact problem.
Yes, the problem seems to be limited to melee.
However
- This problem is not related to mods. I've had this problem since I recently installed the game on this computer (several days ago) via Steam.
- The problem sometimes (unpredictably) corrects itself when I restart the game from the desktop. But only sometimes, and even then animations never line up (I thrust my sword into thin air four feet away, and the bandit dies). This is not a proper fix, since I generally must restart and test half a dozen times or more before killmoves start working again.
- Mods specifically built for the 1.5 update that modify killmoves have not corrected the problem.
I am running Win7 on a Toshiba I-7 2670QM laptop (2.20 GHz) with 8G RAM and can provide further information if it will help.