In the second mission of the RoR campaign Sargon of Akkad, I experience two issues:
Upon driving my relic charriot to the flagged area of Nippur (magenta), the city does not join me, and indeed nothing occurs. I did not kill the orange (Lugal-Zaggisi) units, but this is not required in the objectives. I tried several times, with and withour saving the game, and I never got the city to join me.
When the relic is in a transport ship (with other units), it can be converted to the enemy. This is not a huge problem, but should not occur, I suppose.
FREQUENCY OF ISSUE
100% of the time / matches I play (ALWAYS)
On this image, Nippur is still my enemy. I lost the artefact after my army died, but it was obviously mine upon getting in the area.