Description: After eliminating an AI civilization their icon changes to reflect the civilization is no longer in the game and can’t be interacted with.  After a number of turns the eliminated civilization’s icon flipped back to the regular non eliminated icon.  

Reproducible: (1 / 5) Went back though the save files to see which turn it disappeared on but reloading from the save file fixes the display bug.  

Expected Behavior:  Icon for eliminated player should not switch back to an active player icon.

Confirmed.  I eliminated exactly one AI player and everything went just as you described, so the reproducibility is likely higher than 1/5.

The developers might be able to reproduce the bug by simply eliminating an AI player, then playing on for a few turns, quite possibly nothing more specific is needed.