Baby Skeleton Horses never finish growing up

For some strange reason, baby Skeleton Horses will never finish growing up. They will grow so that they’re nearly the size of an adult, but will never complete their growth.

How to replicate:

1. Spawn a skeleton horse baby

2. (Optional): spawn another baby mob, so you can tell if enough time has passed to allow mobs to grow into adults

3. go do something else for 20 mins to give the skeleton horse a chance to grow, then return

Expected result:

The skeleton horse has grown into an adult.

Actual result:

The skeleton horse has almost completely grown, but has not grown into an adult, and never will.