Before the patch, the thrall command to stop used to be a toggle. Hit stop once it stopped the thrall from attacking and it would stop moving. Hit it again the thrall would attack and start following you again. However, after the patch, the stop command stops the thrall but stop a second time only maintains the thrall in a stopped state.
Also, any command to the thrall used to break them out of the stopped state. But now, commanding the thrall to attack will only attack the one thing you commanded them to attack, then they return to stopped state afterwards.
The return command now seems to be the only command to break them out of the stopped state.