Yes, I have seen this 2nd issue too. I reloaded from a save and moved to the town center tile when entering the city with my other units and then they appeared in combat to defend the city. I reloaded it the other way and found the same outcome if I moved to the lower (off town center tile) prior to the attack and again the units did not enter combat to defend the city.
There also is an odd issue periodically with the caravan units in town center(s) when you try to move into the town, sometimes you can attack them, sometimes you can't move there depending on that unit’s state to your faction (war/friendly).
