After all homebases were relocated, when sending out an army they leave from the previous location of your home city.

I'm not seeing that. I moved my base to the other side of the globe, and the armies are leaving from the new location.

Possibly any armies that were _in_ your home base before it was reset?

Any new ones should go from the new location.

ya that makes sense, It was an old army. I noticed becuase it took like 3 hours to get to a city that was right next to my home base....