Anyone else had this problem? I invested in Cloak and everyone can still see me. Not much use in that.

Never had this problem before playing from my GOTY disks, just the GOG version.

The cloak(s) do not make you silent. You also can't cloak to avoid guards who are already alert and looking for that particular blurry etheral humanoid shape that cloaks and camo vests produce. I'm not pandering, I'm only speculating on the parts you didn't mention.

Yeas, possibly those. I now always Cloak in combination with Run Silent. That seems to help.

You can also cloak after a guard first sees you but his AI is processing it (after his "What's that?" bark but before his "Attack!" bark) and they should lose you.

Furthermore, once you cloak, if you don't cause any more harm to enemies, they'll lose you within about the standard 5-10 seconds of your leaving their line of sight.