All the time pets (including zombies) are getting stuck and ignore commands, including rescue. I couldn't understand what causes that bug, but they seem to reset their behavior after any successful kill. So, if your pet ignores you, kill a turkey for instance, and it will listen you again. The worst here is that you never know if they'll listen you, initiate combat, order to rescue... and nothing happens. :(

Please fix it...

Trying to debug something this general is tough without some kind of log to work from. The chances of a strictly transient error are slim, so if a log can help us figure out what might trigger the behavior (since we have code to look at as well), that would go a long way to solving the problem.