Nevermind!
For some reason, after a refresh (I'm guessing after 12:30-12:40am?), they all were fed and started gaining health again. Though, they were definitely unfed some time before 12am-12:30am while I was typing this post. x:

Link to my stable
Most of my pets (outside the few that I fed individually) weren't fed after the supposed time of feeding. (I can't tell if the amount was properly deducted from my gold though.)