mobs freeze when being pulled by a lead

DISCLAIMER: i have already reported this bug back on February 23 but nobody took notice of it so i decided to make a new one. im NOT trying to duplicate my other report. maybe that other report got deleted somehow. now on to the bug: this is the reason why the leads break when towing a horse, donkey, or mule; they freeze up after a certain period of time. This happens with foxes even if they are not on leads.