As soon as I go into the melee, my character is turned 90 ° and looks to the right, but my camera is just looking and I can not possibly hit the opponent, he always hits the empty because he is also turned.
I have the patch on the GoG also offers normal so 1.2 + 10.2 unofficial.

What can you do there, that's not playable.

You probably have a camera movement key assigned to attack or similar. Check the key binding options, the default keys for camera movement are the keypad keys!