I've just installed EE and I've loaded a game that I started a couple of days ago (started on vanilla 2.0 TW2). I was at the prologue, and I've entered a room in the dungeon where there's a character called "Executioner" swinging a red hot sword at me. I've managed to empty his health bar but he doesn't die! Looking at the damage stats, some of my swings are dealing negative damage (!!!). Casting Ixxi at him won't do anything either.

I'm a complete newb so I don't know if this might be a feature (ie, some characters need to be killed in a special way), but I suspect that this is actually a bug.

OK, I started a whole new game with EE and the bug disappeared.

My hypothesis is that it was caused by using a vanilla save after installing EE...

You know, the forum is filled with people complaining about a "buggy" game while using save games from an "older" title.
On the other hand it would have been nice if CDPR denoted the save game incompatibility.

A lot of people are also complaining about bugs in fresh EE new games, I just want to make clear that this is not the case.

And I say it's a hypothesis that it was caused by using a 2.0 save on EE because I never tried to beat the guy on 2.0, so I can't tell if using an old save is actually the cause (maybe my game was already bugged on 2.0).