Occasionally when you click on a commander for example to examine his stats/magic items etc...the movement order you issued turns to defend instead. This can happen with 14+ commanders when using ctrl/shift to give loads of commanders the same move, examine 1 and all the orders change to defend.
Always use F1 when you have done your turn just to check for any defend orders where there should have been move orders or indeed sneak orders that should be move orders and vice versa.
Your not on your own btw this has caught me out more than once.
