In general; If the galactic map freezes i.e. acts like it is paused, look for the crossed swords battle icon on the map, reload a previous save, and rush that location/planet to prevent said AIvsAI battle that hangs to happen.

If that does not work, it is usually an issue with an event that is bugged that hangs the game. But from what you wrote above you already identified the battle location where the issue occurs, might evenbe a battle between 3 AIs, not sure the game can handle that.

Try to prevent that battle from occuring.

Thanks, I will give that a try.

This happens to my campaigns every once in a while... there's something culminating in the game that's glitching it... sometimes I can revert to a save a battle or a couple battles or day or days ago and I get through the time period with no glitch, but it's extremely frustrating and I kind of hold off on my game play so I'm not investing (or contributing to) whatever is about to glitch the game and then pick up after I'm confident the glitch time period has passed. In the campaign I'm doing now, it was one of the worst, I had to go back several days/battles, took a couple hours to try from each save point only to hit the glitch until finally I went back far enough that the game let me get past it and I was able to continue playing. I'm pretty hardcore with my commitment to playing this game/mod, and I had put a lot of hours and tough battles into my campaign so wasn't about to walk away, but that particular time it almost broke me.
As the previous poster said, if it's a battle-specific glitch, just auto-run the battle... Byss is still a problem planet (for me anyway) and it's 100% crash on initiating a ground battle. Have to run the auto and just plan for the causalities but at least I can keep the game marching forward.