Ryan333: This has absolutely nothing to do with a "buggy Beamdog product". This issue has existed since the original Bioware release in 1998.
Several NPCs have personal quests -- such as Kivan wanting to slay Tazok. If you don't complete those NPCs' quests within a certain time, they will leave your party. They will always give you multiple warnings that they're getting impatient, but when they do finally leave... that's it -- they're gone for good. And they'll take whatever items they had with them. You can find plenty of examples over the years of "I was in the Bandit Camp when Kivan's quest timer ran out -- and he bailed on me right outside Tazok's tent!"
Unfortunately, there's no way to get Kivan (and his gear -- specifically the Gauntlets of Dexterity) back legitimately. But, the Developer Console (aka Cheat Console) can assist.
Look in: C:\Users\{YOUR USER NAME}\Documents\Baldur's Gate - Enhanced Edition for a file called BALDUR.LUA. Open that file in your text editor of choice. Copy/paste the following to the very end of that file:
SetPrivateProfileString('Program Options','Debug Mode','1')
Save and exit, then fire up Baldur's Gate. Load your game, then press CTRL+ENTER. This enables the "debug" (aka "cheat mode") console. Type the following in the chat box:
C:CreateItem("BRAC07")
And there's your Gauntlets of Dexterity.
If you need any other items, here's a good list:
https://gamefaqs.gamespot.com/pc/75251-baldurs-gate/cheats Scroll down to the "Item Codes" section. To add one of these items to your character, use the command:
C:CreateItem("xxxxxx")
...and replace "xxxxx" with the item code from that list.
Good luck!
Kivan never left because of a bug in the classic version. Like Hickory said.