Baby animals acting strange upon relogging

I created a setup to try to automate breeding cow(pic 1). seeing that baby animal hitboxes were fixed i had to try. My idea worked but i had a weird water glitch and decided to relog upon relogging all of my baby cows either jumped and died in the lava or their hitboxes didn't load properly right away. also another box i had the animals in they were no longer in and were scattered around(pic 2).

There are signs holding up the lava on both. My thought was that when the cows aged the could be tall enough to be in the lava, die and the drops would go into the hoppers below, which are snaked aroung to go into a chest.

The 2nd was a test of the same idea, just in a confined area.