I've never experienced this before in the game, but with the GOG version of Thief: Gold, items that you pick up in the game no longer appear in your HUD. Also, arrows that you find don't auto-equip. Aside from the sound effect (loot chime or arrow sound) you don't really know what you've picked up or taken from a chest. Is there a way to fix this? Also, NPCs can't find you if you remain crouched in the dark and will literally walk into you repeatedly without noticing you.

check your game settings in the options (auto pickup). also, Garrett is a master of stealth, remember?

Ah, there we go. Funny, I don't remember there being such an option like that before and I've been playing this game since it came out. Perhaps it's some new edition added by the new dark engine or some other unofficial patch? As for Garret practically disappearing when crouched, maybe the game has always been like that. Thanks for the reply.