Wanted to add to this I had a similar issue with the bolt throwers. When I put on hold fire they kept shooting and when I hit the stop button they would all immediately fire (and not cost any stone)...machine gun bolt throwers. They then stopped shooting but I couldn't get them to fire again when I took the hold fire order off and gave them a target. Eventually they came to their senses and acted normally.
"Death is relative, dear cousin"