/rider command does not allow adult zombies to be carried on horses or other animals

If an adult zombie uses the /ride command to put it on another animal or horse, there's a problem that can't be riding

/ride @e[type=zombie] summon_rider zombie
/ride @e[type=zombie] summon_rider sheep
/ride @e[type=zombie,c=1] start_riding @[type=zombie_horse,c=1]