Summary:
Mobs that can search a water such as axolotls, frogs, turtles are often stuck on the edge of incomplete blocks (mud, soul sand, dirt path, farmland) placed nearby and at the same level with water.

Steps to reproduce:

1. Make a pool (2+ blocks deep).
2. Replace the edges of the pool with the above incomplete blocks.
3. Spawn a mob nearby (frog, axolotl, turtle).
4. Follow the behavior of the mob when he goes to the pool.

Observed results:
Mob went to the edge of the pool and stopped.

Expected results:
The mob should enter the water when it goes to the pool.