Chickens being deleted randomly

I bought a coop and chickens. Every time I open the game to play, I notice some of them were deleted (for example, I'll close the game with four chickens, and open it to find just one). This has been happening for a while (the save game I'm using, where I see this bug, was created around the beginning of March). I've tried checking if they're just unassigned to the coop or lost in household inventory... no show.

In addition, I just noticed one of my rooster chick's got deleted upon aging up, while in game.

Thank you for the attention!