When I try to pick up an Axolotl with a bucket, it is very difficult to get them in the bucket. I can usually find myself several times placing water that was in the bucket, then needing to pick up the water again, and use on the Axolotl, which sometimes may make an entering a bucket sound, but then pops back out into the world. After several attempts, I am able to collect them, but it is very difficult and is likely a glitch.

I am actually using  v1.17.30.22 although Jira says this isn't a version.