I sent an Archaeologist to excavade an antiquity site and the action promp said was on the icon that says choose artifact. I clicked it and nothing happened. I couldn't advance to end the turn except by force-ending with shift + enter. The same thing happened on the next turn. I suicided the architect and the prompt went away, but the antiquity site was gone. Afterwards I sucessfully mined a different antiquity site, with an archaeologist from a different city, and I had already gotten quite a few before. I don't know if the city the glitched archaeologist belongs to will allow me to make a new one. By the way, this happened twice, once with an antiquity and once with a shipwreck. I'm using quite a lot of mods, but I don't think any of them change anything about Archaeology except one... Terra Mirabilis, which changes Mt Vesuvius to give culture on tiles with Antiquity Sites. I'm not sure if that would really cause this, however.