Axolotl cannot be picked up with a bucket in one block deep water, 2 blocks deep water, and sometimes 3 blocks deep water. The axolotl is instantly thrown out of the bucket. This issue seems to be worse if the axolotl is surrounded by blocks which makes picking it up impossible.
Linked issues
Comments

Thank you for your report!
We're tracking this issue in MCPE-44320, so this ticket is being resolved and linked as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.
Quick Links:
📓 Bug Tracker Guidelines – 💬 Community Support – 📧 Mojang Support
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki