Regarding issues with Halo Wars 2 and a recent Windows updates, 343 are aware of this issue and the team are investigating.
You can follow this thread for updates: https://www.halowaypoint.com/en-us/forums/f0258e8001734968984e8b56990f8daf/topics/hw2-game-crash-after-unit-command/13d0a821-3275-4502-ac65-54f15bf4dff2/posts?page=1
You can follow this thread for updates: https://www.halowaypoint.com/en-us/forums/f0258e8001734968984e8b56990f8daf/topics/hw2-game-crash-after-unit-command/13d0a821-3275-4502-ac65-54f15bf4dff2/posts?page=1