Got an archaeologist. Used archaeologist. Made an archaeology dig. Cannot select artifact, cannot create landmark. cannot advance to next turn
Someone already share that bug, it seems to be related to the fact you can buy archeologist with slave.
Fix I have not tested yet :
In the file MODS\JFD's Cities in Development (v 58)\Components\Slavery\Core\Slavery_Units.sql
at the line 110 you will have :
WHERE Cost > 0 AND Mechanized = 0 AND MoveRate IS NOT 'WHEELED' AND NOT Class IN ('UNITCLASS_JFD_WORKER', 'UNITCLASS_WORKER', 'UNITCLASS_JFD_COLONIST', 'UNITCLASS_JFD_SLAVE', 'UNITCLASS_SETTLER', 'UNITCLASS_JFD_GREAT_RECON', 'UNITCLASS_JFD_GREAT_EXPLORER', 'UNITCLASS_JFD_GREAT_AIRSHIP', 'UNITCLASS_JFD_GREAT_ADVENTURER', 'UNITCLASS_CARAVAN', 'UNITCLASS_MISSIONARY', 'UNITCLASS_INQUISITOR', 'UNITCLASS_CARGO_SHIP', 'UNITCLASS_WORKBOAT')
add the unitclass of archaeologist :
WHERE Cost > 0 AND Mechanized = 0 AND MoveRate IS NOT 'WHEELED' AND NOT Class IN ('UNITCLASS_JFD_WORKER', 'UNITCLASS_WORKER', 'UNITCLASS_JFD_COLONIST', 'UNITCLASS_JFD_SLAVE', 'UNITCLASS_SETTLER', 'UNITCLASS_JFD_GREAT_RECON', 'UNITCLASS_JFD_GREAT_EXPLORER', 'UNITCLASS_JFD_GREAT_AIRSHIP', 'UNITCLASS_JFD_GREAT_ADVENTURER', 'UNITCLASS_CARAVAN', 'UNITCLASS_MISSIONARY', 'UNITCLASS_INQUISITOR', 'UNITCLASS_CARGO_SHIP', 'UNITCLASS_WORKBOAT', 'UNITCLASS_ARCHAEOLOGIST')
at the line 115 you will have a very similar query, add unitclass too.
Like this, you and the AI will not be able to buy archaeologist with Slave.
Sadly if i understand the bug, you will have to restart a game or reload the game before you or the AI (difficult to know...) buy archeologist with slave.