why does armadillos keep despawning?

we had armadillos in our base (they’re in our farm) because we made an XP farm and kept two armadillos there. it’s impossible for them to despawn because we bred those two, but they suddenly disappeared.

we explored and found three more armadillos, so we attached them to a ghast and brought them back to our base. but when we reached our base, they all disappeared again 😬😬😬

we don’t know what happened. they were still there when we were a little far from the base, but as soon as we reached our base, they just disappeared 😭 pls help