This was on the Mac if that matters. No Mods. Basically, if you trade artifacts with another Civ, it seems to just fill up from the left with open spaces and doesn't take into account where the traded artifact came from. I'm assuming it just processes them as separate sell/buy transactions. Unfortunately this causes buginess with how the archeologists restrictions work. In the attached file: Trade with Mvemba: The Medieval Chalice in Ngaruawahia for his Medieval Plate Mail, theoretically create a theming museum there (you'll have toss in some gold as well). Instead the Plate mail goes to the empty slot in the capital (Te-Hokianga-nui-a-Kupe), filling out that museum instead. The plate mail can't be traded back to Ngaruawahia, which is now considered a 'not full museum'. And if you go to find the archaeologist Rawiri, who was from Te-Hokianga, and excavate the artifact he was on, he just disappears and doesn't generate an artifact. So I'd have to build a new one again for Ngaruawahia. Now if you excavate the artifact with Rawiri first (filling up Te-Hokianga-nui-a-Kupe). And repeat the Chalice for Plate Mail trade with Mvemba, it works fine. This is relatively minor overall (it's pretty rare I'm swapping with the AI like this, especially before I've filled all my archaeology museums myself first). I'm not sure how hard it would be relatively to add some logic to 'queue up' the empty sold slots first for any bought artifacts.