If I send my soliders to attack an animal den, raider camp, or attacking raiders – and even if I select them and then click on a particular animal or raider – they will just sit there and not attack. However, if I exit to main menu and then restart the game, my soldiers then will attack normally.
Similarly, mounted raiders will sometimes just surround a building and do nothing (raiders on foot and siege engines seem to attack normally). However, if I exit to main menu and restart the game, the mounted raiders will then start attacking buildings normally.