I was pleasantly surprised when we were suddenly able to use our PvP defence monsters for war defence again. However, this change was very short lived as with the update this morning I am unable to use my PvP defence monsters for war again. @Fox was the earlier change a temporary pleasant error or is this recent change back to how it was unintended?

Hi David :)
it is a bug and the fix should arrive tomorrow morning - in about 10 hours from now --
it is also reported here
https://forums.socialpointgames.com/topic/5923/monsters-used-on-defense-in-pvp