Water Mob not Moving Properly

Hello.

I made a custom underground water fish that attacks players.

Here is the problem with it:

• When the fish's target is above it, it refuses to swim horizontally, making it really struggle to kill players or other mobs
• When the fish's target is below it, it moves just fine, just as if it was idling around.

Pages that will likely matter for the solution:

• https://imgur.com/a/7xy6Q1b (Mob behavior)
  https://imgur.com/a/hAztjJL (Mob AI)

Help is very appreciated. Even with years of experience, this is probably my first ever water mob.