I've occasionally, but repeatedly, encountered a problem whereby characters or monsters disappear after I reload a saved game. At one point, for example, a Bullvore disappeared; after I reloaded a save I'd made right before fighting it, there was no more Bullvore. I tried reloading the save multiple times, as well as quitting/restarting the game, and the monster never appeared again. I also encountered this with a nest of Nekkers in Act 2 and endregas in Act 1.

I just had this happen with Iorveth too, as he escorted me into Loc Muinne. I reloaded a save (ironically, I did so just so I could more easily hear his dialogue), and he disappeared. No amount of reloading/restarting restored him.

Anyone know what the issue is here? In the Iorveth case, I'm restarting with a previous save that'll just require me to repeat about 20 minutes of gameplay. But I haven't seen this bug widely mentioned, so I'm wondering if there's some way I can stop this from occurring.

Playing a fully-patched GOG.com version of the game, fwiw. This occurred both before and after the 1.1 patch.

I've never heard of him missing in chapter 3 like you mention, but I have heard instances of him disappearing in act 2 (before he's supposed to), and similarly, Zyvik in Henselt's camp.

Bummer.

I never noticed enemies dissapearing, but with Iorveth and any other "follow the leader" instance in the game this almost always happens. They all seem to end up going to the end of the path they're having you follow so it doesnt break the game, but it's certainly weird and frustrating if you miss dialogue.