my axolotls keep disappearing?! :(

I made a 1.17 survival world and I had 2 axolotl I came back for mining both where gone. I got 4 more 2 baby 2 adult and when I logged back on the babys were gone and I even built walls around them. Right now I just logged off I named one of them and didn't name the other one i,m testing if it has to be named:[ (I did scooped them up in a bucket to put them in the pond)