I am assaulting an independent city named Nok.  After sieging it a couple of turns to build a battering ram, I click assault and manual battle.

The deployment stage never happens.  A message pops up in the battle actions area that says "waiting for confirmation from the Nok".

It is not a computer freeze or anything like that.  All other game actions are still available to me.  I can't progress the game anymore as its continually just waiting for "the Nok" to do something.

Reloading the game at the same turn does not fix the problem.  Abandoning the siege and re-assaulting a few turns later worked.

I had one time a waiting confirmation from the AI for a long time. All I had to do was click out of the battle, and then click back and it was ready to go. Not sure if the same bug as yours.